Introduction to Alloy-free lens production

Introduction to Alloy-free lens production
– Satisloh GmbH –
Introduction to Alloy-free
lens production
Frank Heepen, Product Management Blocking & Deblocking
15.08.2015
V5.1LC
Any given information is not binding, can and will be changed without further notice. In case of
further questions get in contact with the owner of the document frank.heepen@satisloh.com.
-1-
Table of contents
1. OVERVIEW ABOUT TODAY’S LENS PRODUCTION PROCESS ................... - 5 1.1
Traditional lens production ................................................................................................. - 5 -
1.2
Alloy blocking ...................................................................................................................... - 6 -
1.2.1
Alloy compounds ......................................................................................................... - 6 -
2. INTRODUCTION INTO ALLOY FREE LENS PRODUCTION ......................... - 7 2.1
Alloy-free block materials.................................................................................................... - 7 -
2.1.1
OPS process ................................................................................................................. - 8 -
2.1.2
OBM process ............................................................................................................... - 8 -
3. CONSUMABLES FOR THE ART PROCESS ...............................................- 10 3.1
Block pieces ....................................................................................................................... - 10 -
3.1.1
Re-use procedure ...................................................................................................... - 10 -
3.1.2
Manual reading station ............................................................................................. - 14 -
3.1.3
Block piece cleaning .................................................................................................. - 15 -
3.2
Adhesive ............................................................................................................................ - 15 -
3.2.1
Adhesive curing process ............................................................................................ - 15 -
4. SOFTWARE AND CALCULATION ...........................................................- 16 4.1
Job-calculation system ...................................................................................................... - 16 -
4.2
Re-use database ................................................................................................................ - 16 -
4.3
Optimized optical power calculation................................................................................. - 16 -
5. INDIVIDUAL MACHINES AND PRODUCTION STEPS...............................- 17 5.1
Blocking ............................................................................................................................. - 17 -
5.1.1
Automated blocking .................................................................................................. - 17 -
5.1.1.1
Blank and block-piece supply ................................................................................ - 18 -
5.1.1.2
Job identification ................................................................................................... - 19 -
5.1.1.3
Blank loading and recognition ............................................................................... - 19 -
5.1.1.4
Block-piece loading and recognition ..................................................................... - 19 -2Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
5.1.1.5
Adhesive application ............................................................................................. - 20 -
5.1.1.6
Adhesive curing ..................................................................................................... - 21 -
5.1.1.7
Job reject ............................................................................................................... - 21 -
5.1.1.8
Off load .................................................................................................................. - 21 -
5.1.2
Manual blocking (machine being released in fall of 2015) ....................................... - 22 -
5.1.2.1
Job identification ................................................................................................... - 23 -
5.1.2.2
Block rings ............................................................................................................. - 23 -
5.1.2.3
Blank loading and recognition ............................................................................... - 23 -
5.1.2.4
Block loading and recognition ............................................................................... - 23 -
5.1.2.5
Adhesive application ............................................................................................. - 24 -
5.1.2.6
Adhesive curing ..................................................................................................... - 24 -
5.2
Generating ......................................................................................................................... - 24 -
5.3
Polishing ............................................................................................................................ - 24 -
5.4
Engraving ........................................................................................................................... - 25 -
5.5
Deblocking ......................................................................................................................... - 25 -
5.5.1
Automated Deblocking .............................................................................................. - 25 -
5.5.2
Manual Deblocking .................................................................................................... - 27 -
6. PERIPHERALS.......................................................................................- 29 6.1
Manual scanning station ................................................................................................... - 29 -
6.2
Block sorting system .......................................................................................................... - 29 -
6.2.1
Pick to light for job assembling ................................................................................. - 30 -
6.2.2
Sort to ID for block re-use ......................................................................................... - 31 -
6.3
Block cleaning .................................................................................................................... - 32 -
6.3.1
6.4
Amount of blocks to be cleaned................................................................................ - 32 -
Lens cleaning ..................................................................................................................... - 33 -
6.4.1
Manual lens cleaning ................................................................................................. - 33 -
6.4.2
Automated lens cleaning ........................................................................................... - 33 -
6.4.2.1
6.5
Automated cleaning process with UHP150 ........................................................... - 34 -
Off-load-unit ...................................................................................................................... - 34 -
7. LENS PRODUCTION PROCEDURE –MIXED MODE- ................................- 34 7.1
Job calculation ................................................................................................................... - 34 -3Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
7.2
Job ticket ........................................................................................................................... - 34 -
7.3
Re-use database ................................................................................................................ - 34 -
8. AVAILABLE MACHINE DOCUMENTATION ............................................- 35 9. ART PROCESS FLOW OVERVIEW ..........................................................- 35 10.
FRONT SIDE COATED BLANK .............................................................- 36 -
11.
ART COST COMPARISON TO ALLOY ..................................................- 36 -
-4Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
INTRODUCTION
For more than 50 years ophthalmic prescription lenses (Rx) have been fabricated using a production
technique that has involved attaching a raw lens blank to a holding piece (a metal block) using
melted alloy. The alloy compound contains a number of toxic heavy metals now found on the United
Nations Environment Program short term hit list. This fact combined with unstable alloy costs have
caused optical machinery suppliers to enter into a race to see who can be the first to introduce a
practical and cost effective alloy replacement technology. Although one manufacturer introduced a
wax based alternative to alloy back in the 80’s, the wax tended to contaminate other process within
a lab such as the AR coating process (anti-reflective coating) and the wax did not offer enough
support for today’s more sophisticated Rx grinding techniques. By today, with the exception of very
small labs, wax blocking has nearly disappeared from the market.
Satisloh, a Swiss based optical equipment manufacturer, became the first to introduce a non alloy
and no wax blocking technology in 2010 and this technical paper describes the process and
equipment utilized along with its newest version (ART introduced in 2014) which is quickly being
excepted into the global ophthalmic lab market.
1. Overview about today’s lens production process
1.1 Traditional lens production
To produce an ophthalmic lens different machining operations are needed to transform a raw lens
blank into an Rx lens. This process is typically referred to as “surfacing or grinding” and involves
process like milling or grinding, turning and polishing. To hold the raw lens (blank) inside the machine
a work piece holder (block) is needed and a low melting metal (Alloy) connects the block and the
blank (picture 1). The alloy does not stick well on the surface of the blank and can influence the
surface quality and therefore a protection tape must be applied on the surface of the blank before it
can be connected with the block using hot alloy (picture2).
After polishing the lens is typically separated from the block for lens inspection, front- and backside
coating and finishing (edging/glazing). For the last finishing process where the lens gets the edge
shape which is needed for the spectacle frame, this lens must be blocked again to get connected with
the special and much smaller work piece holder for the Edger (picture 3).
Picture 1
Picture 2
Picture 3
-5Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
1.2 Alloy blocking
The most popular Alloy in the ophthalmic industry worldwide is the Alloy 47/117 which has a melting
point of 47° Celsius or 117° Fahrenheit.
This Alloy is easy to melt and because of the low viscosity in the liquid phase easy to apply. The low
melting temperature does not damage the lens blank, but to make sure the block sticks to the blank
and to avoid thermal tensioning it should not be too hot and there is a need to wait 30-45 minutes to
allow the blank to cool down before the next process step can start. After solidification the alloy is no
longer flexible and gives the blank the needed support during the production process.
1.2.1
Alloy compounds
The word ‘Alloy’ describes a mixture of different materials like shown in Table 1 for the Alloy 47/117
and two other Alloys exemplary.
Alloy
Tin
[Sn]
Lead
[Pb]
Bismuth
[Bi]
Cadmium
[Cd]
Indium
[In]
47/117
58/136
79/174
8,3
12
17
22,6
18
44,7
49
57
5,3
19,1
21
26
Table 1
Lead (Pb), Cadmium (Ca) and Indium (In) are all toxic elements and endanger the environment and
the staff in the production lab. There are alloys available which do not have lead or cadmium, but
there is still a big portion of indium needed. Furthermore the melting point of these specialized alloys
is much higher and the price of those alloys is cost prohibitive.
The hidden costs of alloy - As mentioned earlier, some of the heavy metals used in alloy are toxic
and listed in the UNEP hit list. Alloy should be handled in special ways in any lab and the costs of
doing so depend on how compliant a lab desires to be and/or how local government interprets EPA
regulations. Handing and clean-up costs associated with using alloy should include water cleaning
and filtering systems, glove and clothing cleaning/handling, alloy disposal costs, and special reporting
costs. In at least one area of the World, the local government is now requiring labs to conduct blood
testing each month for any employees who handle alloy. The cost of handling alloy is quickly
increasing although the ultimate costs depend on volume used along with a labs interpretation of
compliance. In the US, some labs are now being designated as being alloy Super Users by the EPA
(Environmental Protection Agency). These labs now estimate special handling costs of alloy as being
as ranging from $0.10-$0.40 per lens.
-6Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
2. Introduction into alloy free lens production
2.1 Alloy-free block materials
There are some alternatives to the easy to process but dangerous Alloy process. Products like wax,
hot-melt adhesive (thermo-plastic), putty, plaster or UV-light curable adhesive are known.
To evaluate the materials in a more comprehensive way shows some advantages and disadvantages
for all of them. Wax, like alloy requires a protection tape, is not as stiff as the other materials and is
shown to have a negative impact to the AR coating of a lens. Today’s digital surfacing technologies
require a very firm foundation and the sophisticated designs used are compromised by wax blocking.
Hot-melt adhesive materials also require protection tape and because of the temperature there is a
waiting time between blocking and the next process step. In addition, to date no company has been
able to develop a practical de-blocking technology for either technology. The one advantage of both
technologies is the cost due to being able to re-melt the materials, although this also requires new
steps in the production process. Both technologies utilize expensive metal block which require
cleaning, but they can be reused many times.
Non-Toxic UV-light curable adhesives such as the one used by Satisloh are cured or hardened using a
low heat LED UV light. Because most lenses block UV light, the UV light source must be emitted from
behind the lens (through the block) and therefore this process requires a clear organic block material
that allows UV light to pass. Fortunately there are a number of such materials available in a very rigid
form that can be used many times before being discarded. The advantages of UV curable blocking
adhesives are that little to no curing time is needed, there is nearly no cooling shrinkage (distortion)
and once cured, the material is very rigid making it the perfect foundation for today’s Digital
surfacing turning technologies. In addition, the material allows a lab to block without needing
protection tape and does not contaminate any other process within the lab. The adhesive is even
stable enough to be used within the AR vacuum coating process should a lab wish to keep a lens on
the same block throughout the lab. The one disadvantage of UV cured adhesives is that they cannot
be re-melted and re-used making that one component more expensive than the alternatives,
although eliminating the need for tape makes up for most of the cost difference. In addition, because
tape is not needed, for the first time there is an effective and affordable technology available to
automatically de-block and clean lenses. As a summary, the advantages of UV cured adhesive
blocking are:
•
No hazardous substances like heavy metals to pollute waste water and process waste
•
High-precision blocking
•
Precise blocking without block rings
•
No cooling time due to UV-curing
•
Front side protection by adhesive, no taping needed
•
Machinable block provides stability and full lens support
•
Highly efficient re-use of block-pieces
-7Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
To offer a replacement technology which fulfills the demand of the customers in the different world
wide markets, Satisloh has now introduced two ways to use is ART blocking technology. The OBM
(On Block Manufacturing) and the OPS (Open Platform Surfacing) process. OBM, also sometimes
referred to as One-Block process allows a lens to be held on the same block throughout the entire lab
including AR coating and even edging. OBM requires specialized Satisloh equipment throughout the
lab. OPS, Open Platform Surfacing process is designed for labs who already have traditional coating
and edging in their labs, or for labs that utilize non Satisloh surfacing equipment and in this process
the block is only used in the surfacing process of a lab. The ART blocking equipment used in both
process is exactly the same…the only difference is blocking chuck used to hold the 2 different block
pieces.
2.1.1
OPS process
With the OPS-block piece (Open Platform Surfacing), Satisloh offers a solution which can seamlessly
integrated into existing production lines as the block piece fits all common generating and polishing
equipment. The OPS block, although offering near full support is typical slightly smaller than the front
side blank diameter (picture 5).
2.1.2
OBM process
As a specific version for the Alloy replacement a so called OBM-block piece (On-Block Manufacturing)
is available. The OBM-block is designed as part of the so called OBM line. The feature of such an
OBM-line is that only front side coated lenses are blocked. After complete surfacing the lens remains
on the block and will be coated (Spin- and AR-coating) on the backside. This requires full support
from block to lens to cover and protect the complete front side to avoid pollution during backside
coating (Picture 4).
Picture 4: Full support OBM block
Picture 5: OPS Overlap (block smaller than lens)
Beside the different block pieces both processes are almost similar. Differences will be addressed in
the specific chapters. However, the focus of this document is the OPS process.
-8Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
OBM
Block
ART
Blocking
Generate
Polish
Spin –
Engrave
coat
Deblock
OPS..
Block
Sputtercoat
The same ART blocker can be used for 2 different
production process’s by simply changing the block
piece and holding chuck. A lab using Satisloh’s OBM
manufacturing platform (On-Block or One-Block
Manufacturing) uses the OBM blocks, while a lab
desiring to only replace their blocking in the
surfacing department uses the OPS block (Open
Platform Surfacing).
Topcoat
Edge
Deblock
•
•
•
•
•
•
Toxic, banned by 2020
Surfacing only
Uncontrollable price
Metal block
Cool down period
Requires Tape
•
•
•
•
Alloy Free;
UV curable adhesive
Same OBM block in
surfacing, coating and
finishing.
Block used up to 5x
Only for SL equip
•
•
•
•
•
Alloy Free;
UV curable adhesive
Same OPS block in
surfacing & spin coating
Uses less adhesive
Block Used up to 100x
Works on any equip
-9Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
3. Consumables for the ART process
3.1 Block pieces
To optimize optical power and to reduce the amount of adhesive there are 5 different block
curvatures introduced. Those are 60, 80, 110, 180 and 500mm to cover a working range of plano
(0dpt) lenses up to 35mm (15dpt).
Those 5 different blocks have the same diameter which is 65mm for the OPS block piece and 75mm
for the OBM block piece. The bigger OBM block diameter is caused by the need to cover and protect
the whole frontside of the lens to avoid getting the coating of the backside displaced on the
frontside.
The block material is SAN (Styrol-Acryl-Nitril) which is machinable and can be cut down together with
the lens to a smaller geometry to give the lens the best support without overlap of lens to block.
Picture 6: OBM block style
Picture 7: OPS block style
3.1.1 Re-use procedure
Both ART block piece versions can be used more than once to save cost and to reduce the amount of
waste in the production lab.
OPS block pieces can be used up to 100 cycles. After 100 uses, the mechanical wear and/or reduced
ability to pass UV light could lead to reduced lens quality.
OBM block pieces are limited to 5 cycles because of the build-up of process residue which can
interfere with the vacuum coating process as well as mechanical wear which will end up in reduced
lens quality.
Identification of right block type (curvature)
Five different front-curvatures of the block pieces are available for optimized fit of different blank
base curvatures. This blank to block combination defines the space between both curvatures and
therefore the volume of the adhesive to fill out this ‘space for maximum lens support. For ‘full
support’ application no overlap of final lens diameter to block is allowed. Optimizing the match
- 10 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
between the block curve and diameter to the lens blank front curve not only maximized design
quality but also minimizes the amount of glue required significantly reducing glue cost.
For the identification of the correct block style a so called ‘cut-off-table’ exists. Table 1 shows which
blank base-curvatures will be combined with the different block curvatures. The table can be made
accessible in a labs LMS (lab management software) and can be modified by the customer, if needed.
Table 1: cut-off table
Determination of the right block diameter
Depending on the specific customer production situation, see Diagram 1, the original block diameter
(65mm for OPS or 75mm for OBM) will be reduced by the generator. For best lens support by means
of the block the overlap of final lens diameter in relation to the block diameter must be smaller than
4mm therefore, additional block diameters like shown in Table 2 are defined.
Diagram 1: variation of final lens diameter
Table 2: Block diameter
The lab LMS is calculating the right block-diameter according Table 1 and Table 2
This information about the best diameter (group) and base curvature (block style) will be printed on
the job-ticket to give the operator the needed data to put the correct block piece in the job tray.
Table 3: Block style and diameter on job-ticket
- 11 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
Scenarios for matching block-blank diameter combination
-
-
Block diameter is bigger than final lens diameter
Block will be cribbed down during generating process together with the lens. Normal
situation for new OBM block pieces. Gives best support. Optimal combination.
Block diameter is the same as the final lens diameter
Full support possible. Normal situation for re-use on OPS and OBM blocks.
Block diameter is smaller than the final lens diameter
Normal situation on OPS on any lens diameter above 65mm as well as on OBM on lens
diameter above 75mm. Cleaning of lens needed. Total amount for overlap of final crib to
block diameter depends on customer quality expectations.
Same situation as in the Alloy-blocking process. Bending issues expected.
Selection scenario (example)
Referring to table 2 the following situation, for a 60mm lens diameter, can occur:
- LMS calculated 60mm as the needed block diameter
o 60mm blocks are available  Operator takes 60mm
o 60mm blocks are not available  Operator has to choose the next bigger one which
is 65mm. If this is not available he has to choose (only OBM) the 70mm or then 75
mm diameter.
*
The most customers accept or do not look for optical power issues on the last 2 mm of the lens.
Live scenarios for OPS block pieces:
-
A new 65mm block is used the first time for a
o 65 to 80mm lens diameter
 This block stays in group ‘65’ and can be used again for any other lens
diameter as long as the maximum amount of usage cycles is not reached
o 60 to 64mm lens diameter
 This block moves to group ‘60’ and can be used again for any lens diameter
equal or smaller than 60 mm as long as the maximum amount of usage
cycles is not reached
o 55 to 59mm lens diameter
 This block moves to group ‘55’ and can be used again for any lens diameter
equal or smaller than 55mm as long as the maximum amount of usage cycles
is not reached
o 50 to 54mm lens diameter
 This block moves to group ‘50’ and can be used again for any lens diameter
equal or smaller than 50mm as long as the maximum amount of usage cycles
is not reached

o Smaller than 50mm lens diameter
 This block is smaller than the minimum diameter now and is going to
‘recycling’
- 12 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
Block to Blank combinations
OPS
Block
group
Final lens diameter
66
65
65
stays in
60
should be
64
63
62
61
60
59
58
57
56
55
goes to next smaller group
55
stays in group
stays in group
no
goes to next smaller group
should be avoided
54
stays in group
no
no
stays in
Usage of blocks if 3 different block diameters are defined (65, 60 & 55mm)
Block
group
65
Final lens diameter
66
65
64
63
62
stays in
61
60
59
58
57
56
55
goes to next smaller group
55
should be avoided
54
no
stays in group
no
stays in
Usage of blocks if two different block diameters are defined (65 & 55mm)
OBM
Block
group
Final lens diameter
71
70
69
68
75
67
66
64
63
62
61
60
59
goes to next smaller group
70
65
65
goes to next smaller group
should be
avoided
60
stays in group
stays in group
should be avoided
55
goes to next smaller group
stays in group
stays in group
should be avoided
Usage of blocks if 5 different block diameter are defined (75, 70, 65, 60 & 55mm)
Block
group
Final lens diameter
71
70
75
65
69
68
67
66
65
goes to 65mm group
should be
avoided
stays in group
stays in group
64
63
62
61
60
no further re-use possible
no further re-use possible
Usage of blocks if two different block diameters are defined (75 & 65mm)
- 13 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
59
Oval block shapes
In principle a block, if cribbed oval or noncircular to the centre, can be re-used to.
-
-
-
Block can be used according to the b-axis for a round shape with a smaller or same diameter
as this short axis. A-axis information needs to be provided to the Blocker as well as to the
generator to avoid a ‘crash’ situation.
Block can be used based on b-axis for an oval shape where the new a-axis is smaller or same
as the new b-axis. A-axis information needs to be provided to the blocker as well as to the
generator to avoid a ‘crash’ situation.
If the customer is blocking the same axis all the time, - blocks can be defined as a new blank
group and used again for those oval shaped lenses with the same or smaller dimensions on a
and b- axis.
Because of the adhesive application procedure where the adhesive is applied in the centre of the
block, it is not possible to give an oval cribbed lens - full support by an already oval shaped block
even if both dimensions for a and b-axis are the same.
All noncircular shaped blocks are not used for further re-use cycles.
Parameter for ‘end of live’:
3.1.2
Diameter less than 50mm
Amount of ‘allowed’ re-use cycles reached (5 for OBM; 100 for OPS)
Mechanically destroyed e. g. by water jet: chipping, scratches…
Datamatrixcode no longer readable
Soiling of block (e. g. polishing slurry) which cannot be removed by washing
Manual reading station
To identify block pieces e. g. after manual Deblocking or cleaning an identifying process is required to
make the data for the actual diameter and the amount of use-cycles for the specific block visible to
the operator.
The information of the data matrix code will be scanned and the block-information will be requested
by the re-use database.
Feedback from the database such base curvature, amount of use-cycles, actual dimensions (a- and baxis) and to which diameter group the block belongs will be displayed on a screen.
Every Satisloh OBM and OPS block piece has a unique Data Matrix Bar code printed on it that can be
read by the ART blocker and de-blocker. Usage database tracks number of uses, curvature and
diameter information so that automatic or manual systems can be used to sort or dispose of blocks.
- 14 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
3.1.3
Block piece cleaning
During multiple use-cycles process fluids like polishing slurry or water will dry and accumulate on the
block piece and make it difficult to read the data matrix information on the block. In addition the
adhesion force to the block is affected.
Therefore a cleaning process is required twice during the lifetime of an OPS block at 34 uses and 67
uses. The re-use database is tracking the number of uses and gives information to the automated
Deblocker or to the manual scanning station about the need for cleaning.
See chapter ‘Block cleaning’ for more information about cleaning procedure and equipment.
3.2 Adhesive
To connect the blank with the block piece holder - an ultraviolet (UV) -curable adhesive is used. The
cured adhesive is machinable like the blank and the block piece itself and does not contain any
hazardous substances. Toxic waste handling at the end of the lens production is no longer required.
The adhesive is a mixture of different components with an oligomer acrylate as the main component.
Picture 8: Bucket with adhesive
3.2.1
Adhesive curing process
The curing time depends on the thickness of the adhesive layer. The thickness itself depends on the
match between the block- and the blank curvature as well as the decentration and prism which
might be needed for the specific job. Therefore the curing time differs between 5 and more than 30
seconds.
The operator is protected from exposure to ultraviolet radiation by the Plexiglas cover of the Blocker.
No special P.P.E. is required.
- 15 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
4. Software and calculation
4.1 Job-calculation system
Like in the Alloy process, all jobs will be calculated in a system like Rx-pert, Rx-universe or the
systems of competitors like Lensware, DVI, Visionstar, and OptiFacts. Because of the different block
piece geometries the calculation system has to define the right block and has to take this block-piece
data for calculating the relevant labels like _LBLHI or SVAL.
Table 4: Block height
4.2 Re-use database
To track the lifetime and the actual dimensions of - block pieces a so called re-use database is
required. This database is connected to the ART-Blocker and the automated ART-Deblocker and can
be connected to the (Satisloh) Generator as well. The re-use database can be used in conjunction
with various competitor equipment.
The Blocker sends a request to the reuse database after scanning the data matrix code and
identifying the individual serial number of this block.
As - feedback the blocker gets the information about the dimensions of the block (a- and b- axis) and
the base curvature. If all data fits the job information the blocker takes the block and continues the
process. In case of a mismatch the blocker rejects the block and is offloading the blank and block
back into the job tray.
If the maximum number of use-cycles for cleaning or ‘end-of-life’ is reached the automated
Deblocker is sorting the block into a specific bin inside the machine. In case of a manual reading
station this information will be shown on a screen to give the operator the information about how to
sort the block back for further re-use, for cleaning or for ‘end of life-time’.
4.3 Optimized optical power calculation
The ARTAutoBlocker measures base curvatures of any blank. As an option this data can be send back
to the LMS system. The actual curvature, which is more precise than the data of the blank supplier, is
therefore known in the system. This data can be used to calculate the back curvature to get an
improved optical lens power. Option available only for spherical front side lens surfaces.
- 16 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
5. Individual machines and production steps
5.1 Blocking
Satisloh now makes two different non-alloy ART blockers. A manual version for low volume labs, and
an automated version for high volume labs.
5.1.1
Automated blocking
Picture 9: ART-Blocker-A
The blocking process is called ‘spatial blocking’. This means there is no block ring between the block
and the blank which gives the geometrical height orientation including prism or decentration during
the solidification of the UV adhesive same as for Alloy blocking. The blank is secured by a ‘pick-uphead’ during the curing cycle.
The automated Blocker is able to block all organic lens materials and blank styles like SV, PR, Bifo and
Trifo. In addition the Blocker can block up to 5,5 degrees of prism.
- 17 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
Mineral lens materials:
If pattern recognition is needed the quality of the back curvature is important and should not
influence the imaging process. Almost all mineral blanks have a strong pattern caused by the mould
in a shape of a spiral or parallel lines (see picture 10). Spherical mineral blanks can be blocked.
Picture 10: Mineral blank
5.1.1.1
Blank and block-piece supply
An automated production process requires blank and block in the tray. Different options are
available to fit the conditions at the customer like ‘block in tray’, shown in picture 11 and ‘blank on
block’, shown in picture 12. In the first version (block in tray), the block is located in the rear part of
the tray by a special insert fits either OBM or OPS block and a transfer loader inside the blocker
moves the block over from this position to the opposite side of the tray where the blocker can pick it
up. The second option uses a different tray insert, the block piece is located below the blank in the
same location currently used in an alloy process. The benefit of this ‘blank-on-block’ loading option is
that the rear part of the job tray stays free and customers can still use this area for putting frames or
work tools in the tray. Blocks can be loaded in the tray up room as operators load blanks into the
trays. SL also makes available a pick to light system to assure that tray up personnel load the right
blocks into the tarys. It should be noted that SL will introduce an automated block loading system in
early 2016.
Picture 11: Full support OBM block
Picture 12: OPS Overlap (block smaller than lens)
- 18 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
5.1.1.2
Job identification
Similar to the Alloy process the blocker scans the job ticket and requests the job data from the LMS
system. If valid feedback is received from the LMS, the blocker takes the job data and the automated
blocking process will start.
If the job data is not valid, the job will be automatically rejected by the blocker to minimize lost
production time.
5.1.1.3
Blank loading and recognition
The lens blank if transferred from the job tray to the imaging station through the use of an
automated loading system.
In the imaging station the blank will be mechanically centered by two gripper arms (left side on
picture 14).
If the job requires the machine to take into account axis orientation of the blank – all non SV blanks –
the video recognition software takes a snapshot of the pattern visible on the front surface of the
blank (see picture 13). This is achieved by using an IR light source in combination with a high
resolution camera. The imaging station is covered by a metal shield to protect the operator and to be
independent from individual light conditions in the production area.
Imaging station
With gripper
Measurement
station
Picture 13: Full support OBM block
Picture 14: OPS Overlap (block smaller than lens)
After successful imaging the next step is measuring the base curvature - By using a tactile process
with 33 pins (right side on picture 14) the front side will be touched to get the information about the
height profile (geometry of the front side).
5.1.1.4
Block-piece loading and recognition
The block is loaded into the machine while it is recognizing the blank. After the loader takes the block
out of the tray the machine is scanning the block data-matrix-code (see picture 15). The information
about the block-style and the block diameter is required. It has to fit to the job data (block
- 19 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
geometry). The machine compares the information and continues the process if the actual block
matches the requirements and rejects both the block and blank if this condition is not met.
Picture 15: Full support OBM block
5.1.1.5
Adhesive application
The blocker uses the measuring station (right side on picture 14) to determine the correct amount of
adhesive to dispense. This is essentially a calculation of the volume of space between the lens blank
and the assigned block piece. Factors such as block dimensions and blank dimensions along with
prism requirements are used in this calculation. The goal is to minimize the volume of adhesive
necessary while maintaining a high level of quality.
The adhesive is applied directly onto the block using a delivery system which pumps adhesive from a
storage container (see picture 16) up to the dispensing valve (see picture 17).
Picture 16: Storage container
Picture 17: Dispensing valve
- 20 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
5.1.1.6
Adhesive curing
To cure the adhesive a LED based UV-light source is used. The light source is in the lower part of the
machine under the blocking station. The UV light passes through the block to the adhesive and blank
material (see picture 18)
Picture 18: UV curing station
The curing time depends on the thickness of the adhesive and is about 7 seconds per mm. In this
particular case note that the lens was lowered onto the block and glue at an angle to block a certain
degree of prism. This patented process called spatial prism blocking eliminates the need for prism
rings.
5.1.1.7
Job reject
The blocker is looking for valid job data, compares the given data from the job file to the measured
data of pattern and base curvature of the blank. In addition the block piece will be identified. In case
of any type of mismatch the machine will not block the lens to avoid breakage. This comparison will
be done for each lens separately which means that in case of a job with two lenses where only one is
rejected the second will be blocked.
5.1.1.8
Off load
In case of a reject the blank and the block piece are transferred back to the tray and the Blocker
provides a so called ‘bad-job’ signal to avoid moving an unblocked lens to the next machine causing
an error there.
This signal can be used in different ways.
- The blocker writes the information ‘bad-job’ back to the LMS and the LMS takes care that the job
will not be accepted by any other machine in the production process until the job is not completely
done by the Blocker.
- The tray can be stopped at the last stopper and must be taken off by hand. This stops the
automated lens production process.
- The signal can be detected by a plug at the blocker to use it for a so called ‘off-load-unit’ to
automatically take the job out of the production process. Such an off-load unit can be a tray-stacker
which picks the ‘bad-job’ or a separate conveyor -.
- 21 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
After feedback from the off-load-unit about taking over the bad-job from the blocker, the blocking
process continues.
5.1.2
Manual blocking (machine being released in fall of 2015)
The manual Blocker is able to block all organic lens materials and blank styles like SV, PR, Bifo and
Trifo. Beside this the Blocker can block prism of 1, 2, 3, 4 or 5 degree but unlike the automated
blocker, this machine does require the use of prism rings. A manual blocker is perfect for a small
volume lab (less than 150 j/d) or as a complement to the ART autoblockers for out of range jobs.
Mineral lens materials:
If pattern recognition is needed the quality of the back curvature is important and should not
influence the imaging process (almost all mineral blanks have a strong pattern caused by the mould
in a shape of a spiral or parallel lines). The operator is able to differ the unwanted pattern on the
backside and the needed pattern on the frontside and do the axis adjustment in the right way.
Picture 19: ART-Blocker-M
- 22 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
5.1.2.1
Job identification
By manually scanning the job-ticket the Blocker requests the job data from the LMS system and
displays the relevant job data on the screen.
Relevant job data for the operator are: block-style, block-diameter, block ring, prism axis.
The operator can setup the manual blocker as a stand-alone unit if no LMS system is available. In
addition to the information below, the machine needs input data of blank-style and blank-diameter.
5.1.2.2
Block rings
The manual Blocker does not measure the front curvature of the Blank. Block rings will be used to
give the blank the needed height orientation including prism and decentration (see picture 20).
There are 6 different block rings available with 0°, 1°, 2° 3° 4° and 5° of prism.
The insertion of the block ring is the first step in manual blocking.
Pick up head
Blank
Prism ring
Picture 20: Full support OBM block
5.1.2.3
Blank loading and recognition
The blank will be taken manually out of the tray and placed on the block ring. If the job requires the
need to control the axis of the blank – all non SV blanks – the machine displays a live image of the
lens blank. The image is displayed on the screen. The blank can be moved to the correct position and
orientation manually to align with the specific markings displayed by the image recognition software.
5.1.2.4
Block loading and recognition
The block will be taken manually out off the tray and placed into the block reception.
The operator has to control the block-style and the block diameter.
- 23 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
5.1.2.5
Adhesive application
The blocker is calculating the correct amount of adhesive in regards to the space between blank and
block (same as the automated process).
The adhesive comes from a metal bucket using a so called drum pump outside the machine (same as
automated process).
5.1.2.6
Adhesive curing
To cure the adhesive a LED based UV-light source is used -. The light source is in the lower part of the
machine under the blocking station. The UV light passes through the block to the adhesive and blank
material (see picture 21).
Picture 21: Full support OBM block
The curing time depends on the thickness of the adhesive and is about 7 seconds per mm.
5.2 Generating
OPS block pieces can be used with generators without any adaptation. It has the same geometry as
the Alloy-block piece. The only exception is an additional axial beam in the collet chuck of the
generator for the Alloy process. This axial beam is sometimes used to avoid a 180° axis loading error
due to an operator putting the lens in the tray using the wrong orientation in the . Such an axis beam
is not needed for the ART process but can cause errors in a mixed production mode if Alloy and ART
blocked lenses will be generated in the same Generator.
The geometry of the OBM block piece is different to the Alloy block piece. Because of this difference
a special clamping chuck is needed for the generator.
If an Alloy blocked lens must be generated in a generator with the clamping chuck for OBM, special
Alloy block pieces are needed.
5.3 Polishing
ART does not generally require any different parts in the Polisher or a special polishing process.
For the Polisher Duo-Flex in combination with OBM lens production lines an optimized washing
station (02-061-408) is mandatory to avoid contamination of the COB-coating module. This washing
option is recommended for all ART installations if automation is the focus.
- 24 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
5.4 Engraving
ART does not require any different parts in the engraving process.
5.5 Deblocking
Deblocker is available in either manual or automated version to fulfill different customer
requirements worldwide.
In contrast to the Alloy process it is possible block a blank with a smaller diameter than the block (or
better than the block ring). Because of the specific conditions in the deblocking process the final lens
diameter has to be bigger or the same as the block diameter.
5.5.1
Automated Deblocking
Picture 22: ART-Deblocker-A
The automated Deblocker separates block piece, lens and adhesive by using a high pressure water
beam with about 150 bar water pressure (picture 23, 24).
- 25 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
Picture 23: Deblocking chamber
Picture 24: Deblocked lens
A 40 liter water-tank is inside the Deblocker. A high-pressure pump is located in a movable housing
outside the Deblocker.
After successful deblocking, the lens will be put back in the job tray, the block piece will be sorted
according to block-style and block-diameter into 12 different bins inside the Deblocker (see picture
25). The adhesive stays in a mesh in the machine as well for disposal at a later time.
Picture 25: ART-Deblocker-A
The lens will be blown off on both sides by using an air-knife system (see picture 26). Small amounts
of water can remain on the lens after the drying process is done. The lens is not clean enough for an
optical and cosmetic inspection or coating. It is recommended to do an visual inspection including
cleaning straight after deblocking to avoid water spots on the lens surface, to separate lenses which
could not be deblocked and to peel of adhesive residues which sometimes stays on the lens.
- 26 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
Picture 26: Air knife system
To speed up the deblocking process the automated Deblocker is working with warm water with a
temperature of 50 degrees Celsius.
Water will be heated up inside the water tank and must be replaced regularly to avoid contamination
of the lens because of glue particles in the water. Replace the water manually or after a specific
amount of deblocking cycles has been reached.
5.5.2
Manual Deblocking
Picture 27: ART-Deblocker-M
- 27 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
The manual Deblocker separates lens and block by using a high pressure water beam with about 150
bar water pressure. A 60 liter water tank is mounted on a movable slide-in cart inside the Deblocker
along with the high pressure pump.
Depending on the blank material or front side coating the adhesive stays either on the blank or on
the lens and must be peeled off by hand.
Regarding the five different block-styles the operator has to select the right template inside the
Deblocker by a handle (see picture 28).
Handle
Templates
Picture 28: Handle and templates
The water must be replaced regularly to avoid contamination of the lens due to glue particles in the
water. Replacing water is done manually.
- 28 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
6. Peripherals
6.1 Manual scanning station
Picture 29: Manual reading station
On multiple process steps like, matching block pieces and blanks for the job, sorting back after
manual Deblocking or cleaning the block piece, identification of a block piece is needed.
This manual scanning station consists of a block piece adapter with an integrated scanner, a
computer and a screen.
After scanning the data-matrix code on the block the information about the block-style, the blockdiameter, the diameter group the block belongs to and the use-cycles are shown on the screen. In
addition the correct bin for sorting back will be shown as well.
This station is also able to scan the bar-code on the job ticket. In this situation the information about
the needed block data like block-style, block-diameter and the diameter group the block belongs to
are shown on the screen. In addition the bin of where to pick the block piece will be shown as well.
6.2 Block sorting system
The functionality of the ‘manual reading station’ is implemented in a block piece sorting and a block
piece identification system, developed by NCC, to make the Tray-up at the job assembling area or the
identification for further re-use after deblocking or cleaning more convenient. Those systems are
able to manage 12 different block styles, like described at chapter 3.1.1
- 29 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
6.2.1
Pick to light for job assembling
Picture 30: Pick to light station
Picture 31: Bin identification
In the assembling, or tray-up, area a PTL (pick to light) system stores the block pieces for jobassembly. After scanning the barcode on a job ticket the job information will be shown on a screen
and in addition buttons light up under the bin where the right block is in (see picture 31). After
pushing the confirmation button the system is ready for the next assembly. PTL process flow is
shown in picture 32.
Picture 32: Manual reading station
- 30 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
6.2.2
Sort to ID for block re-use
Picture 33: Sort to ID station
Picture 34: Bin identification
After deblocking or cleaning the blocks can be identified by a S2L (sort to ID) system. This system
offers the opportunity to let the block dry before they can be used again.
After scanning the QR-code on the block the information about which bin this block belongs to is
shown on a screen (see picture 34). S2ID process flow is shown in picture 35.
Picture 35: Manual reading station
- 31 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
6.3 Block cleaning
Picture 36: Ultra sonic block cleaning station
To clean block pieces an ultrasonic cleaning bath like Satisloh’s SW-12 (Article 01-050-477) with a
portion of 3% of cleaning agent OP164 (Article 92-000-121 or 92-000-179) and a 10 minute cleaning
cycle is sufficient.
The number of block pieces to clean is approx. 11 pieces for one blocker in an 8 hour shift.
In case of adhesive residue on the block, which is more often seen with manual deblocking, this
residue must be peeled off by hand before the block can be used again.
If a data matrix code is not readable the block piece must be checked. The area of the data matrix
code can be cleaned manually by using light alcohol with a cloth used for manual lens cleaning or
simply wiping the block piece off with a finger.
6.3.1
Amount of blocks to be cleaned
How often a block must be cleaned within the life time depends on the situation at the customer like
washing process during/after Polishing and water replacement for manual or automated Deblocker.
The number of cleaning cycle within the life time of the block can be calculated with the formula
below. So far the expected cleaning cycle is 34
maximum 𝑢𝑠𝑒 𝑐𝑦𝑐𝑙𝑒𝑠
�−
𝑐𝑙𝑒𝑎𝑛𝑖𝑛𝑔 𝑐𝑦𝑐𝑙𝑒
�
100
�−
34
�
1=3−1=2
1 = 𝐶𝑙𝑒𝑎𝑛𝑖𝑛𝑔 𝑐𝑦𝑐𝑙𝑒 𝑤𝑖𝑡ℎ𝑖𝑛 𝑏𝑙𝑜𝑐𝑘 𝑙𝑖𝑓𝑒 𝑡𝑖𝑚𝑒
How many block pieces must be cleaned each day can be calculated with the formula below.
- 32 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
𝑙𝑒𝑛𝑠𝑒𝑠 𝑝𝑒𝑟 𝑑𝑎𝑦
�
𝑚𝑎𝑥𝑖𝑚𝑢𝑚 𝑢𝑠𝑒 𝑐𝑦𝑐𝑙𝑒∗ 𝑐𝑙𝑒𝑎𝑛𝑖𝑛𝑔 𝑐𝑦𝑐𝑙𝑒 𝑤𝑖𝑡ℎ𝑖𝑛 𝑏𝑙𝑜𝑐𝑘 𝑙𝑖𝑓𝑒 𝑡𝑖𝑚𝑒
�
Example 1:
1 ART Blocker; 70 lenses/hour; 8 hour a day
560
�
100 ∗ 2
�

= 𝐵𝑙𝑜𝑐𝑘𝑠 𝑡𝑜 𝑐𝑙𝑒𝑎𝑛
1 * 70 * 8 = 560 lenses a day
= 11 𝑏𝑙𝑜𝑐𝑘𝑠 𝑡𝑜 𝑐𝑙𝑒𝑎𝑛
Example 2:
6 ART Blocker; 70 lenses/hour; 12 hours a day 
5040
�
100 ∗ 2
�
6 * 70 * 12 = 5040 lenses a day
= 100 𝑏𝑙𝑜𝑐𝑘𝑠 𝑡𝑜 𝑐𝑙𝑒𝑎𝑛
6.4 Lens cleaning
Like in the traditional Alloy process lenses must be cleaned before quality inspection or coating.
6.4.1
Manual lens cleaning
Residue of adhesive and/or adhesive and process water mix which can contaminate the lens surface,
can easily be wiped off with a cloth and a light alcohol like isopropyl (IPA) used for lens inspection.
6.4.2
Automated lens cleaning
Picture 37: SCL auto cleaning system
Traditional US- or brush systems can be used to clean the lenses after deblocking. Depending on the
specific machine and the additives the customer is working with, a process adaptation might be
necessary. Additional cleaning might be necessary if glue residue remains on the lens.
The well known company SCL, located in France, offers a fully automated lens cleaning machine
UHP150 which is optimized for the ART process and shown in picture 37. This machine cleans residue
from polishing liquids and adhesive remnants. In some seldom cases the glue layer or bigger parts of
- 33 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
it can remain on the lens after deblocking. Therefore it is recommended to install a manual
inspection between deblocking and automated lens cleaning.
6.4.2.1
Automated cleaning process with UHP150
The UHP150 cleans the already deblocked lenses in 6 steps
Step 1: Polishing removal
Step 2: Tap water Rinsing
Step 3: Adhesive removal
Step 4: Tap water Rinsing
Step 5: DI water rinsing
Step 6: Drying with compressed air
6.5 Off-load-unit
A tray stacker or an additional conveyor belt can be used as an ‘offload’ unit to pick up jobs which
were rejected by the Blocker. For this function the ART-Blocker-A offers a specific plug where the
‘reject signal’ can be taken in a handshake scenario.
7. Lens production procedure –mixed modeThe traditional alloy process and the ART process can be used parallel. This makes it possible to use
only one LMS or job calculation system. However it is not possible to mix OBM and OPS and Alloy
production at the same time. It is either OPS or OBM together with Alloy
7.1 Job calculation
No need to define blocking process during job-calculation!
E. g. RxUniverse is calculating all needed parameters for both blocking processes. If the Job is done at
an Alloy-blocker the next machine gets the already pre-calculated information. If the job is done at
an ART-Blocker the LMS takes back the blocking information and overrides the relevant labels.
7.2 Job ticket
Both information for ART and Alloy is printed to the ticket. The operator is able to see which
OPS/OBM block is the right one and which Alloy block and block ring fits the job.
7.3 Re-use database
The re-use database uses data from our VFT generator to always get the correct information for the
block diameter into the database. If the job was done on ART-Blocker the label ‘BLKTPY’ changes its
information as soon as the Blocker writes back the specific labels. The VFT looks to the label ‘BLKTYP’
and knows if there is a need to send data back (ART) or not (Alloy).
- 34 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
8. Available machine documentation
In Table 5 all available machine documentation is listed.
Operation
Spareparts
Transport
Software
Maintenance
Service
ART (OPS)
Automated
Manual
Blocker
Deblocker
Blocker
Deblocker
G
G
G/E
G
G/E/F
G/E/F
G/E/F
G/E/F
G/E
G
G/E
G
(G)
(G)
X
G/E
G/E
G
G
ART (OBM)
Automated
Blocker
Deblocker
Blocker
(G/E)
G
G/E/F
G/E/F
G/E
G
E
G
E
G
Manual
Deblocker
(G/E/F/S/I)
G/E/F
(G/E/F/S/I)
X
(G/E/F/S/I)
(G)
Table 5: Machine documentation
G – German
E – English
( ) – preliminary version
F – French
S – Spanish
I – Italian
X – not needed
9. ART process flow overview
The ART process flow is very similar to the Alloy process, which is a precondition for a replacement
purpose.
- 35 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
10. Front side coated blank
The ART process fits coated and uncoated Blanks in general. The benefit of using a coated lens is
faster deblocking (manual and automated) as well as less effort on lens cleaning.
11. ART cost comparison to Alloy
Because of the specific conditions at any customer (such as production volumes, labor rates,
depreciation schedules, and alloy clean up costs), it is not possible to do a generic cost per lens
calculation.
An Excel based calculation sheet is available where various parameters such as depreciation
longevity, labor rates and production volumes can be manipulated to come up with a cost estimate.
For more precise comparison please get in contact to Product management
(frank.heepen@satisloh.com)
- 36 Introduction to Alloy-free lens production, Frank Heepen
© Satisloh
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