American Tooling & H.I. Materials

[Pete Hanlin]

I would like to gather some opinion regarding the future of tooling in our labs...

As far as I can tell, a lab that considers itself to be in "good" shape has 1.530 tooling in 0.10 diopter increments. This situation allows good accuracy on CR-39, Trivex, Mid-Index, and Polycarbonate materials. However, as 1.60, 1.67, 1.71, and future 1.74 materials become more prevelent, how precisely will the average laboratory be able to grind prescriptions?

For example, let's say a 1.74 index material is released (we'll make it SFSV spherical, for the sake of argument). Let's assume the 6.00 base has a true curve of 6.05 diopters. The manufacturer is able to provide the product with a +/-0.02 tolerance for front curvature.

Now, trying to grind this lens to a -1.00 the lab would need a tool that will create a surface with a power of -7.05 on the back of the lens. Converting to the tooling index (1.530), the tool selected would be 5.00, which would provide a curve with a true power of -6.98 (0.07 weak). Add in the manufacturer's tolerance on the front side, and you are possibly up to 0.09 diopters off the intended power- which leaves only 0.03 diopters of play for all the other processes in the lab before the lens is out of ANSI tolerances.

Now, I realize that- in my example- I took a very low power (I doubt there would be many -1.00 lenses surfaced in 1.74). However, my point is this: as indices get higher and higher, tooling in 1.530 is going to become less and less accurate. When surfacing CR-39, rounding only loses you a maximum of 0.04 to .045 diopters of accuracy when you are tooled to 0.10. However, in an index like 1.74, you would be giving up 0.07 or more of accuracy in some situations (and that is assuming your tools are all accurate- which is a false assumption in many, many American labs).

So, my question is this- is the average American lab prepared to surface the ultra-high index materials that will come in the near future? Or, will the introduction of these premium products simply accelerate the demise of the independent, mid-sized laboratory?

Thanks for your responses!

[Jeff Trail]

Pete,

A few things to consider, first as you pointed out, your example maybe "biased" in the power spectrum. I would think to even go a step further and saying I would doubt you would ever see someone in a -1.00 going for a 1.74 index (that would be crazy, both in pricing as well as optical quality :)) so lets move down to a range where you would start, realistically, using those high indexes and where that tolerance is in acceptable range under the ANSI :-) ...
You might also be giving the higher indexes (atleast in my own opinion) more "volume" than actually is being used.. when you break down ANY lab out here premium indexes are the minority of materials being processed by a long shot.. as much as some people would like it to be different CR39 is still the vast volume king in the average wholesale lab (well CR307 is up there as well if you want to toss in all Transitions) than polys, mid indexes, glass than the higher indexes 1.66 and up ....I also would not include 1.60 in that list of materials where lens and tools start to become a problem .. any lab running tools in 10's and not 12th's have no problems in the 1.60 and below ...
As for the other parts, if you actually want to see where we are headed (high probability) is take a look at DAC's inflated tool system cylinder machines..it would be cost effective to place this in if the volume warranted it for the production of the 1.67 and up if it did become a production problem (off power fluctuation)
Looking at the production numbers in rate of volume the amount of super high indexes are still on the low end of the volume scale and most probably always will be if you sell and use the index to fit the RX. A lot more average RX's out here than those that want and or need super high indexes.
BTW if I had an optical and put that -1.00 sphere in a 1.74 I hope they would REVOKE my ABO for being unethical!! :) (I know you just "picked" a number for an example..but couldn't help throwing a "jab")
I think we tend to get to much into the "technical" side and getting ahead of ourselves in thinking about this (I am guilty as the next guy) and forgetting about comparing actually usable dispensed volume in material choices.
Also a thing to consider is the vast amount of these super high index materials are coming out in SV and PAL's most often and not bifocals, so with SV you always have the choice of going with factory molded lens often and the ranges available are fairly wide... and since in aspherical or atoric you can NOT use any prism to decenter and surface on center if you get a "finished" version or surface it in-house in these cases going factory is less expensive and no different in thinness etc., etc.
Looking at the "big picture" I don't think it will make any difference one way or the other "volume" wise to wholesalers in general. I just wished all you guys (Essilor and on and on) would give us some of those super high indexes in a FT version .. I have tons of choices already in the SV area but nothing in the FT in that area.
BTW cranked out a few of the 1.67's from Essilor yesterday for one of my accounts.. even used the 12ths in tools and they came out right on the button (according to my digital lensometer from Reichert) :cheers:

Jeff "just my . 02 worth, can't wait to see more opinions" Trail

[Pete Hanlin]

I think we tend to get to much into the "technical" side and getting ahead of ourselves in thinking about this (I am guilty as the next guy) and forgetting about comparing actually usable dispensed volume in material choices.
Manufacturers have to stay ahead on the technical side of things- lest they launch products that turn out to be too difficult for their customers to process.

The percentage of Super High Index (n=1.67 and above) is relatively small. However, it also represents the premium product market. Labs that are unable to produce these products are going to be at a competitive disadvantage (because, as you know, your account might start out sending only specialty work to your competitor, but once your competitor has a foot in the door s/he will work for all of your account's business).

Even if we all agree 0.10 tooling indexed to 1.530 is adequate for today's materials, wouldn't it make sense to advise labs that are updating or installing new tool sets to purchase tools indexed higher? A tool set indexed to 1.67 is going to be more accurate for all materials- not just high index- because the radii difference between the steps will be smaller.

[Joann Raytar]

Pete,

For the amount of lenses, Indices 1.70 and above, that are going to be run, wouldn't labs running surface lathes that cut laps just cut laps?

[Jeff Trail]

Jo,

If you want to see the wave of the future (besides things like the Q2100 :)) check out the DAC lathe system and cylinder machine that two "lap" fit any and EVERY job (well a couple of sets of laps) I saw a demo of this system and it is amazing how "precise" it is cutting curves down to the EXACT curves..and than you place it on the "bladder" tools and it fits exactly for the final "polish" out.
Pete's point of view is thinking industry wide.. but from my point we are already starting to fracture as wholesalers. Some looking for that big simple volume and playing cut throat on the middle of the road PAL's.. and if you wanted to look for the guys that began this Pete only has to look down the hall way :) Varilux and now HOYA and a few other companies have forced labs and opticals to have multiple accounts (wholesale) and glass has even fractured it further.
Some of my accounts have three and four labs they use, of course labs are not blamless either they started giving out lost leaders in low prices on the low end (SV and bifocals) and than making it up on the premium side and that has been back firing for years since most retailers started using multiple labs and shifting work where they could save the most money.
I have even restructured my prices a time or two over the last five years (going backwards BTW) to stay competitive so as much as we might find it leaving a bad taste in our mouths (wholesalers) we are going to continue to see this trend continue where you find your spot and make that part grow and be thankful when other things gets throwed into the daily orders. Now that the lens companies have pushed advertising and marketing into the mix by passing labs and even retailers at times and going public you either join them or fight'em any way you can but that is just the landscape of optics now (for better or worse)
I think one of the main problems Pete will run into from his end is that Essilor has deep pockets and when you come up with this "new lens" and decide on you technical information you might come up with the process that is needed that will only be done by the most advanced wholesale labs anyway, the average lab out there in a OD or retail store who is running an SGX and not wanting to install some high end system on top of that (like the DAC system at $176K or so for the lathe and cylinder machine) being bypassed any way...IF you think only high end than you are ignoring a wide piece of the market place.. that is "in store" labs and the smaller labs.
Also another .02 worth :-) ..what am I up to a dime yet? .. a little off the topic of the thread but still part of the over all debate (I think)

Jeff "grind'em if you can get'em" Trail

[Darryl Meister]

You can actually quickly determine the potential rounding error of your lap tools with the following computation... If you have 1.530 tooling and a lens material with a refractive index of (n), multiply the tooling increment (e.g., 0.10 D) by (n - 1) / 0.530. This is the new, effective tooling increment. Then divide this number by 2 to determine the potential rounding error.

For instance, consider a 1.74 high index material and tenth-diopter tooling... Your potential rounding error becomes:

0.10 D x (1.74 - 1) / 0.530 = 0.14 D

0.14 D / 2 = +/-0.07 D

Best regards,
Darryl

[shanbaum]

Pete, the simple answer to your post is, you're right. 1.530 tooling in .10D is not a particularly clever formulation. When labs started running poly, 1.53 in .12D produced poorer results than labs were accustomed to seeing in CR-39; using .10 increments in 1.53 is a little closer to .12D increments in 1.586 - so, cylinder powers come out a little closer in poly using 1.53/.10D. The results in CR-39 aren't harmed as much as those in poly are improved because of CR's lower index.

There seems to be a movement underway towards using a higher index for tooling, the most common case being around 1.60; the reason for choosing a number in that vicinity is that it produces cross curves that correspond to cylinder powers in CR-39 (498/600 *0.30 = 0.24D), which still comprises a fair percentage of production for most labs.

The method not mentioned so far, which is certainly the best approach (and the one used most frequently outside the U.S.) is to cut laps in the index of the material to be processed on them, which means, a set of laps for each index. That's not as awful as it sounds, because in that case, cross curves are required in only quarter-diopter increments (since that's the way 99.999% of Rx's are written).

The advantage of this approach is that it creates a direct correspondence between the powers sought and the curves on the laps.

With the panoply of materials & indices that has appeared over the last decade, having a different set of laps for each material is less practical. When a small number of materials makes up most of a lab's production, Jo's suggestion is a good solution - have laps for those primary materials, and cut laps for the marginal ones.

If one has to be able to process lenses of unpredictable index, then the answer is, obtain the smallest increment practical. It doesn't matter in that case whether one increases the index, or decreases the increment, unless one is trying to skew to set to favor a particular index as described above.

And lastly, laps should be compensated for the thickness of the pad to be used in fining & polishing. While it has become commonplace to "let the computer do the compensating", this reflects a fundamental misunderstanding of what the computer can do: while it can pick different laps (steeper ones) based on compensation required, it can't change the curves on the laps. When laps are cut without compensation, the effect of the pad will have a varying effect on the power of the resulting curves, across the range of laps. That means, the difference between one lap, and the laps on either "side" of it incrementally, will differ depending on its curve. This violates a basic tenet of robust process design, which is, to the extent possible, one should enforce uniformity; processing any one workpiece should be as much like processing every other workpiece as it can be made to be.

To express this in practical terms: when laps aren't compensated for pad thickness, the power produced by the cross curves on the laps becomes dependent on the base curve of the lap. Which is to say, you won't have two laps of differing bases, which can produce exactly the same cylinder power. It also means that the difference between two lenses' sphere powers which can be produced (assuming that there is a difference), depends on the base curve of the blank selected - the difference between (for instance) a 6.00 base curve and a 7.00 base curve will not be the same as between an 8.00 and a 9.00.

As Jeff mentioned, there are systems on the market today which eliminate the need to have set of laps altogether. In addition to the recently-announced DAC system, there's Gerber Coburn's Gemini system, which has been in actual use for some years now.

[Pete Hanlin]

You mentioned compensation for pad thickness, which brings up another scary issue with tooling in American labs.

Namely, I've seen quite a few labs that have "C" marked on some- but not all- of their tools. You guessed it, upon measuring the tools it turns out some are compensated and some are not. Even worse, with the advent of gripper pads and such, tools purchased at different times may have different amounts of compensation.

As you mention, the best approach is to use tools matched to index of refraction (the Japanese do this, and can control the back side of their lenses with tremendous precision).

What I am wondering is why we don't specify tools by radius of curvature? After all, that is what we are really after when we use a tool to produce a curve.

Here is my proposal for a suggested standard for tool sets:
Use the radius to denote tools, and use a range of .060 to .250 (.0005m increment between steps at the flatter curves, working up to .008m increments at the high end).

So, tools would be marked thus:
.0600 sph
.0600 .0595
.0600 .0590
.0600 .0585

.250 sph
.250 .242
.250 .234
.250 .226

and so on...

I have a feeling such a system might be a bit confusing, but it would theoretically solve some of the other confusions our current system leaves us with. Tools would no longer be of a particular index- nor would there be "compensated" and "uncompensated" designations.

[shanbaum]

Pete Hanlin said:
Here is my proposal for a suggested standard for tool sets:
Use the radius to denote tools, and use a .002m increment between steps. This provides power steps of about 0.11 on 1.7 and steps of about 0.09 on CR-39.

I would think a lab so equipped would be in very good shape.

Yeah, but you think voting for George Bush was a good move, too.

Equal increments in radius would produce varying increments in power across the range of laps. For example, using a 2mm radius increment, consider: a 124.5mm-radius curve is 4.00 diopters in CR-39; a 122.5mm radius is 4.06D; a 55.33mm radius is 9.00D; a 53.33mm radius is 9.34.

Or, looking at it the other way

radius(mm) - power (1.498)

50 - 9.96
52 - 9.58
54 - 9.22
...
100 - 4.98
102 - 4.88
104 - 4.79

I can't think of any compelling reason to mark laps in radius, mainly because I can't see how the numbers would be particularly informative.

[Pete Hanlin]

In fairness to Shanbaum, he was posting in reference to my original post (which had equal increments across the range).

In fairness to me, I had already thought of this and saw his response after I had reposted...

;)

As for the rationale- as mentioned earlier, it would eliminate indexing of tools and compensation. It would be easier to increase the accuracy of the set, since it would merely be a matter of shrinking the increments.

Anyway, it seems to me American labs are going to have to update and improve their tooling situation through one means or another if they are ever going to achieve real accuracy on high index products. I mean, we aren't working on developing additional LOW index materials (well, except for Trivex, but we won't go there... oops, just did).

PS- I'm not so sure we'll be seeing a huge proliferation of bladder-type finers/polishers in the forseeable future. Also, the concept has yet to be proven in a high volume environment.

[Michael Walach]

Robert is allways right, BUT :p

I do have some problem with the concept of compensated laps.
When lab has only one set of laps and employing various pad systems for different materials or curve ranges you are back to square one.
Pertaining to hi-index lenses over 1.6, DAC system or Gemini is the best solution. However, if lab does not have DAC or Gemini the alternative method for surfacing hi-index material lenses is to cut disposable lap EXACT! The few cents extra economicaly surpasses poor lens power quality or rejects. And last, there are many other factors that determine the power of the lens, for example: ROUNDING, TOOLING INDEX, BLOCKING METHOD, TOOL EVALUATION METHOD, etc.

Michael Walach

P.S. I do agree, this Bush deal was a boo-boo.

[jofelk]

It is early Monday morning and I am trying my best to rationalize the problem.
If a formula is used to figure a curve and it spits out a -6.05, regardless of index, the tool is rounded to the nearest available in the lab. You could be off by .05, .07, etc. The closer the gap in tooling the less error.

[shanbaum]

Michael Walach said:
I do have some problem with the concept of compensated laps.
When lab has only one set of laps and employing various pad systems for different materials or curve ranges you are back to square one.

Well, close to square one, but - in how many labs is a given lap being used with pads of varying thickness?

Until recently, this was almost impossible - all pad systems were the same thickness.

Now, it may be possible, but one might reasonably argue against the practice (of using multiple pad systems). There is merit in uniformity (at least when it comes to manufacturing).

[Michael Walach]

Robert Shanbaum said:
Well, close to square one, but - in how many labs is a given lap being used with pads of varying thickness?

Until recently, this was almost impossible - all pad systems were the same thickness.

Now, it may be possible, but one might reasonably argue against the practice (of using multiple pad systems). There is merit in uniformity (at least when it comes to manufacturing).

Hello Robert:

In my experience many labs are using pads of different thickness
according to the lens material. For Poly it might be 0.64 mm, two-step CR39 0.457 mm, one-step 0.42mm, gripper pads 0.82 mm, etc.

Yes is is not the best manufasturing practice--but s... happens.

Michael

[Pete Hanlin]

It is early Monday morning and I am trying my best to rationalize the problem. If a formula is used to figure a curve and it spits out a -6.05, regardless of index, the tool is rounded to the nearest available in the lab. You could be off by .05, .07, etc. The closer the gap in tooling the less error.
Yes, but the phrase "regardless of index" doesn't work because the tooling (like the lens material) does have an index.

Most tooling is indexed at 1.530. When you pull a tool that reads "6.00" you are pulling a tool that will create a 6.00 diopter surface on a 1.530 lens material only (assuming the tool is indexed to 1.530). In other words, if you have a Trivex lens with a perfectly flat front surface and you use that tool to produce a curve on the back of the lens, the lens will read exactly -6.00 diopters. This is because Trivex has an index that matches the tooling index. However, use that SAME tool to create a curve on the back of a perfectly flat-fronted 1.67 lens and the lens will read 4.75 diopters- because the lens has a higher index of refraction than the tooling.

Here's the problem. Let's say the next tool in the set is 6.10. Use that tool to create a curve on the back of our flat 1.67 lens and the power will be 4.825. In other words, the "tenth" tooling is only capable of providing 0.125 diopter increments when making 1.67 lenses. Even worse, if the next available tool in the set is 6.125, the gap between powers becomes 0.15 diopters.

Point being, the preciseness of the tool set decreases as the lens material's index increases.

Well, close to square one, but - in how many labs is a given lap being used with pads of varying thickness?
Probably not too awful many (at least too awful many that KNOW they are). Follow me here... You have "compensated" laps which were made assuming a pad thickness of 0.15mm. They are dutifully stamped with a "C." For some reason, you replace or add a lap. Since you have a compensated set, you order a compensated lap- but compensated exactly how? The company providing the lap asks your tech what kind of pads they use and the tech says "We use the Gripper system." So, the company sends you a lap compensated by 0.4572mm. Now you have a wrongly compensated compensated lap. Same problem if the wrong compensation is entered into the Lab Management Software.

All this to say I simply feel that compensated laps were a bad idea from the start. If all manufacturers used the same front curves it might have made some sense to compensate laps to provide 0.125D increments for given curves- but this isn't the case.

When it comes down to it, laps/tools are used to create curves- not powers. Seems we should designate them by the actual curves they create.

[Pete Hanlin]

P.S. I do agree, this Bush deal was a boo-boo.
Yeah, I agree... I'd have felt much more secure these past couple of years under the steady-handed leadership of a stand-up guy like Albert Gore.

(Now pardon me for a moment, I need to go pour a stiff one- a shiver just ran down my spine.) :D

[jofelk]

Again I may be over simplifying the problem.
Using 1.530 tooling, .12 increments, with a base curve of .50 and wanting a -6.00 sph.
Index of material = 1.499 tool = -6.87 error = 0
Index of material = 1.523 tool = -6.58 error = .04
Index of material = 1.586 tool = -5.93 error = .06
Index of material = 1.67 tool = -5.25 error = 0

[shanbaum]

In other words, if you have a Trivex lens with a perfectly flat front surface and you use that tool to produce a curve on the back of the lens, the lens will read exactly -6.00 diopters. This is because Trivex has an index that matches the tooling index. However, use that SAME tool to create a curve on the back of a perfectly flat-fronted 1.67 lens and the lens will read 4.75 diopters- because the lens has a higher index of refraction than the tooling.


No, the 1.67 lens will have a power of -7.58. You calculated backwards.


All this to say I simply feel that compensated laps were a bad idea from the start. If all manufacturers used the same front curves it might have made some sense to compensate laps to provide 0.125D increments for given curves- but this isn't the case.

When it comes down to it, laps/tools are used to create curves- not powers. Seems we should designate them by the actual curves they create.


Equally incorrect; the end product we produce are spectacles, and laps are used to create lenses of specific powers. Because we know the set of powers we're going to need to create, it is only rational to design the set of laps to produce those powers. Uncompensated laps cause the available power increments (both sphere and cylinder) to shift significantly across the range of laps.

You confuse the means with the ends.

Admittedly, when processing lenses on laps which do not match the lenses in index, this effect is already present.

The front curves used really have nothing to do with it - unless you're suggesting that it's common practice to mix lens vendors on a single pair of specs.

[Pete Hanlin]

No, the 1.67 lens will have a power of -7.58. You calculated backwards.
Got me... I'll cite exhaustion and carelessness as my excuse. Hope I didn't make the same error in the article I wrote on this subject for Laboratory Product News (just checked my file- happily, I didn't... look for the article in your next edition).

Uncompensated laps cause the available power increments (both sphere and cylinder) to shift significantly across the range of laps. You confuse the means with the ends. Admittedly, when processing lenses on laps which do not match the lenses in index, this effect is already present.
No, I still reject your line of thinking on this point. Compensation for the thickness of a pad should be done when calculating the curve required to effect a curve with the proper power- not "rigged" into the tool used to create the surface. Labeling a tool -6.00 -6.25 C simply involves too many ambiguities. Namely:

• -6.00 -6.25 at what index?
• Exactly what amount of compensation does "C" indicate?

In my opinion, the problem is similar to the "warp" factor built into some lab management software. Basically, an extra variable is being built into the system that doesn't need to be there.

Curves create power- tools create curves. They should be notated by the curve they produce- not by their power in some arbitrary index.

PS- Considering that Robert is a leading authority on lab calculations and software development (and considering the entire industry accepts dioptric measurements as the method for labeling tools), I am willing to concede that I am just being a Devil's Advocate at this juncture.

[Pete Hanlin]

Again I may be over simplifying the problem.
Using 1.530 tooling, .12 increments, with a base curve of .50 and wanting a -6.00 sph.
Index of material = 1.499 tool = -6.87 error = 0
Index of material = 1.523 tool = -6.58 error = .04
Index of material = 1.586 tool = -5.93 error = .06
Index of material = 1.67 tool = -5.25 error = 0
I think we are both correct given the vantage point we are using to view the issue. To simplify my point, all I'm saying is- using the tool set you describe (0.12 increments in 1.530 tooling)...

If my front curve reads 0.00 (PLANO) and I use a tool marked 6.00, the power that results on each material is:
5.64 = CR-39
6.63 = Poly
8.37 = 1.74 (it already exists and will eventually be coming to the US)

The problem (at least in my opinion) comes when I jump to my next tool (6.12). Now I create:
5.76 = CR-39 = 0.12 increment
6.77 = Poly = 0.14 increment
8.54 = 1.74 = 0.17 increment

Considering that we need to stay within 0.12 diopters for most lenses to pass ANSI (and the demands of our accounts), UHI materials are becoming more and more difficult to accurately process as long as 1.530 is used as our index for tooling.

(Robert will have to check my math to make sure I went in the correct directions- but I think I'm with the program this time round.)
;)

[jofelk]

Pete I think I see where the problem is.
When we process a lense we start with a formula that uses the index of the lense and inject the Rx, which gives us a tool curve, notice the flow of procedure.
The required tool could be, but not only, from 0.000 to 20.000. If tooling is in .12 increments, I use this as a worst case, then the nearest tool is used creating at worst an error of .06.
The formula is used on the sphere and cylinder creating two curves, each with an error no greater than .06. If in the worst case both tools are rounded with the .06 error then the resulting error would equal .12.

[jjconcepts]

after running through you well written, eltremely informative tennis match (had to throw that in) I am left with two questions on my mind.

1. was the original question answered?
So, my question is this- is the average American lab prepared to surface the ultra-high index materials that will come in the near future? Or, will the introduction of these premium products simply accelerate the demise of the independent, mid-sized laboratory?

2. being that manufacturing is done in tolerences - in all industries. at what point does putting out a pair " just this tide of tolerance"- as I have heard quite often- become poor manufacturing and require an update to the system.

american labs - at least the ones I've run with can process(in tolerence) anything i've had to run. update ansi, update tools, or just cut a lap for the client who demands better than industry standard tolerance. I believe that as an rx is written in .25 increments, a great range of error has occured at the beginning - therefore opening a wide grey area that would be interesting to explore.

[Pete Hanlin]

The required tool could be, but not only, from 0.000 to 20.000. If tooling is in .12 increments, I use this as a worst case, then the nearest tool is used creating at worst an error of .06.
Yes, I think we have arrived at the same destination... Put another way, if you took the same tool set and remarked it with the powers it actually creates on a 1.67 index, your 0.12 incremented 1.530 tool set would look like this on the rack...

6.00 SPH
6.00 6.16
6.00 6.32
6.00 6.48
6.00 6.64

6.16 SPH
6.16 6.32
6.16 6.48 ...and so forth

Notice that if you have a 6.00 base front side and you want to create a plano lens with -0.25 cylinder the closest you can possibly come is -0.32 cylinder (-0.07 off)? Add in a couple hundreths of a diopter for front curve tolerance (manufacturers have tolerance leeway as well) and a hundreth or two for all the surfacing processes (blocking, generating, fining), and you are bumping right up to your +/-0.12 ANSI tolerance.

So, my question is this- is the average American lab prepared to surface the ultra-high index materials that will come in the near future? Or, will the introduction of these premium products simply accelerate the demise of the independent, mid-sized laboratory?
...and that is the question here, isn't it? I believe there is and will continue to be a need for the independent laboratory. However, I can also anticipate that it is going to be more and more difficult to prosper as a mid-size in the coming years.

Having accurate tooling is just one small symptom of the problem. The equipment being developed today is primarily aimed at mass production of Rxs. Take a cut-to-polish generator that can spit out a pair every minute or so and you're talking about lens production that could only be dreamed of a few years ago. Once laboratories with these wonder generators actually work themselves into the proper mindset of how to really maximize their performance, you will see lower and lower production and breakage costs for large labs with modern equipment.

However, if I own a lab doing 350-500 jobs per day, I am probably not quite in the market for a single generator that can churn out a full day's production in 6-9 hours- especially since I'll have specialty work that probably won't be produced on this expensive piece of equipment. Ditto for automated blockers, tapers, etc.

So, who really needs automation? Unfortunately, unless a laboratory has very efficient and enforced procedures for every lab process (and exceptionally few do), breakage is a natural occurance. In years past, breakage was accepted as "a cost of doing business." Today's designs and materials, however, are neither tolerant of loose procedures- nor are inexpensive enough to spoil without eating significantly into the bottom line.

Drill mounted lenses are a prime example of this same problem. It seems as if most of the lenses in this niche (if 20% of all jobs can be called a niche) are high index ARC lenses. If a lab is still using a hand drill to process these jobs, they're going to spoil lenses. These lenses aren't cheap, so profits on drill mounts is going to be dramatically impacted.

Fortunately, there is automated equipment that can greatly increase the accuracy of drill mounted work (but it still requires skilled operators who know how to calibrate the equipment and mount lenses properly). This equipment costs money, however. Money the small-to-medium lab may not have to spend on a drill machine.

In my opinion, only mid-sized labs that understand and implement an effective Quality Management plan are going to survive- and these will probably do very well, since there will always be people who value the individualized service independents specialize in. Really, the only LARGE labs that are going to do well are those that understand the need for well-controlled procedures.

The ophthalmic lab business is changing. Breakage is no longer easily written off as an expense- it is becoming a larger and larger factor in profitability. Economy of scale is also becoming more and more important.

Sorry for the length... I've really enjoyed this thread in Ophthalmic Optics (except for the part where Robert caught me getting sloppy with my figures!).
;)

[shanbaum]

I'm not sure how the Devil would feel about you claiming to be His advocate, Pete, since I know there's not an evil bone in your body. Except, maybe, when it comes to politics.

OK, you object to compensated laps because you think they are marked ambiguously. You cite two reasons in asking, "what index" and "what compensation".

"What index" is ambiguous regardless of whether the tool is compensated or not, so that's really not an appropriate objection to compensation.

"What compensation" is a reasonable objection - although, as I pointed out in an earlier post, until recently, and going back to the introduction of abrasive pads around 1974, the stack of fining pads, and the polish pads, used in processing plastic lenses, have always been 0.018" (or 0.457mm). With the introduction of a number of "gripper" systems, I can't really argue that there's only one pad thickness. But from a GMP standpoint, I can't see any justification for using more than a single thickness of pad (or pads) on any given lap. Sure, you can do it; but you shouldn't.

So the answer to "what compensation" should really be as obvious as "what radius" - that is, the lap should be compensated according to the pad to be used on it, just as it should be cut to the "right" radius. Neither is obvious by just looking at a lap - sometimes it's a little hard to tell what the design parameters were by measuring the lap. If the information marked on a lap is insufficient, well, there's no law that says a compensated pad must have a "C" on it. If not knowing in what index, and with what compensation, a lap is cut and marked, is a problem, there's no reason why that information can't be marked on the lap explicitly.

The problem that is created by using uncompensated laps that I want you to understand is this: it needlessly creates a dependency between the power differentials you can create, both in terms of sphere and cylinder power, and the particular laps you use, in terms of where you are in the set. That is, if you have an Rx like this:

-175 -50 180
-150 -25 180

Pretty common Rx, no? Now, depending on the lens design - mainly, whether it's aspheric or not - and material index, you might use either a four, or a six base lens. My point is this: using uncompensated laps, the difference in sphere power between the right and left lenses will be different depending on whether you use a four or a six, as will the cylinder powers be different.

That's bad.

If the lenses and laps match in index, and are properly compensated, while you may have some rounding error on the sphere curves, the sphere powers will differ by exactly 0.25, and there will be no error on the cylinder power (not the total power, but the magnitude of the cylinder - which is the objective; the total power error will be the same as the sphere power error). Running the job on one base curve or another may affect the rounding error on the sphere powers, but will not affect any of these other important values (i.e., the difference between the two sphere powers, and the cylinder powers).

That's better.

Whether or not the lenses and laps match in index, if the laps aren't compensated, different laps will produce different power differentials. A 600/700 will produce a different cylinder power than a 700/800. The difference is sphere power between a 600/650 on the right and a 625/675 on the left will be different than that produced by using an 800/850 on the right and an 825/875 on the left.

Whoops. That's bad, again.


Is this sinking in, Satan?


Now, regarding how all this relates to the future of labs, the fact is that most labs with which I'm familiar either have gone to, or will be going to, some other configuration than the traditional 1.53/0.12D. Most are adopting an index around 1.6 and increments of 0.10D, and most are not compensating for pad thickness, because they're listening to bad advice like that offerred by my friends Michael and Pete. I have to assume that I'm simply not explaining myself clearly enough, as my logic is impeccable. Or maybe the lab managers are just being pococurante.

In any case, a new set of laps is not a monumentally expensive proposition.

I also wouldn't worry too much about the high-priced new technologies wiping out the little guy - this sort of thing will "trickle down"; now there's something Pete should understand.

I also wouldn't assume (as Pete does) that "automation" is invariably synonymous with "low breakage"; nor is the elimination of fining necessarily synonymous with "high productivity" (or "low breakage").

[Pete Hanlin]

I had a conversation with Satan (well, really I asked a friend who has regular conversations with him- scary), and he has kindly granted me permission to speak on his behalf on this thread only (nice fellow, really, given his reputation- btw, he says "Hi" from the Kennedy brothers).
Hey, you're the one who said I'm evil when it comes to politics! ;)

Anyway, I do understand your point on the compensation issue. The problem is similar to the one I encounter with my "mark tools by radius" theory. Namely, equal changes in radius of curvature effect power to a greater degree on flatter curves because the change represents a greater % of the radius.

The ability to adapt one's opinion based upon intelligent discussion (or maybe even discussions like this ;^) is the mark of reason. Therefore, I'll grant that I will reconsider my opinion on the compensation issue- provided we agree that some marking on the tool should indicate what the compensation actually IS.

Regarding automated equipment- you are incorrect. I do not assume that automation = automatic higher quality. If that were true, a VERY expensive retail owned lab that we are both familiar with should be producing very high quality work- which it is not.

However, automated equipment raises the quality potential of a laboratory. This is precisely why I said: Really, the only LARGE labs that are going to do well are those that understand the need for well-controlled procedures.

As for "trickle down," I want to commend you for trying to apply the best economic model of the 20th century. Unfortunately, we have a long way to go on setting you on the correct path. Money given to corporations and investors does trickle down to the people who work in said companies and produce the goods that investors inevitably purchase. Technology doesn't always have the same tendancy (really man, when is the last time you VISITED a real lab???).

Since you work for an equipment manufacturer, perhaps you can explain what kind of equipment you will be producing aimed at the small-to-mid-sized lab in the coming years (you know, something designed to produce less work rather than more). Then I'll be happy to talk all about the next new, lower index product- whoops, that would be Trivex, and Essilor didn't buy into that stuff. Guess I'll have to let our Hoya and Younger friends talk about that marvelous wonder-material (I hear it has an abbe value in the 40s!!! ooohhhhh, wow!).
:D