I need advice on viable measuring techniques (lenght)

squeekyduck

Hi folks,

I need to order a device that is capable of measuring up to 300mm lenghts accuratly.

At present my op's are measuring lenghts of up to 300mm using a microscope and a ruler. This method is not viable as they have to drag the product and ruler from right to left as the measure.

I have been looking at toolmakers microscopes, but do they measure up to 300mm? The accuracy needs to be up to 0.1 of a millimeter.

We have a shadowgraph on site also, but using this method is time consuming as ops must leave their lines, measure and record and return. Is there any more methods or tools that can be used?

Thanks

CatFromHue

im not sure what you mean by drag the ruler from right to left

but have you thought of using a verniers?

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0431583

squeekyduck

Thanks for your reply.

Unfortunatly a verniers would be a high risk tool for damaging our product. The product in question is a medical device.

What I mean by dragging left to right;

The product is put on the rulers edge and viewed under the microscope. Due to the constraint of the microscope only measuring say 10mm, the op must drag the product that is sitting on top of the ruler across the viewing field of the microscope in order to measure it. The risks involved are; the product can potentially get damaged or the product may slip away from the top of the ruler giving an inaccurate measurement.

Figerty

Hello,

By the sounds of it, you can't risk the product being damaged on it's ends or a vernier would suffice. It sounds to me that you need a fixture designed and built to hold the device properly and repeatably to allow measuring.

One way would be to set up a moveable table on a linear slide that would slide 300mm under the microscope. It would need to be aligned properly, and it would be dependant on the workholding requirements. Establish your reference edge and move 300 mm (slip guages) then the difference in the length + or - the 300 mark is your measurement.

It's unlikely you will buy an off the self system, unless you look at buying a vision system which would be very expensive.

dan_d

(I have nothing to offer, however when I saw your thread title I thought "a measuring tape...?"
Sorry:o)

who_am_I?

for non-contact measurment you need a CNC vision system, Nikon, OSG Or Mitutoyo are probably best for your application, more exocitic systems such as Infinite Focus or Mycrona may be necessary for very difficult applications.
at a push you could use an inspecvision system for a 0.1 tolerence, but it may not be suitable

fabbydabby

Have you considered a template? Or do all the products have totally different lengths?

Alright

I agree with who_am_I?


http://www.nikoninstruments.eu/en_ZW/Products/Measuring-Systems/Vision-Systems/NEXIV-Confocal-VMZ-K6555

http://www.nikoninstruments.eu/en_ZW/Products/Measuring-Systems/Vision-Systems/NEXIV-VMR-12072

If you've a big budget buy something like above...

Not sure what you're doing, how accurate you have to be, how you handle
the specimens that need to be measured or how much you can spend but
there are lots of inspection equipment companies out there.

Maybe try to buy some second hand equipment from a 300mm
semi-conductor FAB in Asia or the States?

I'm not sure if that helped?

who_am_I?

Tool makers microscopes traditionally have a very short travel on the stage (up to 50 mm), these have micrometer heads on the stage.

Measuring microscopes have larger stages fitted with linear encoders and a large digital readout of position, this is what you asked about.

Regarding Expense, in general you can expect the following.
Measuring microscopes cost around 10-15k,
Manual Visions systems cost around 15-20K
CNC vision systems cost around 20-30k
Cheaper systems from china and second-hand systems are available.

The advantage of vision system it it will print a report and send data to an SPC package and the measurement process is repeatable.

Depending on the circumstances, it may be more difficult to pass gauge R&R with the measurement microscope due to variation introduced from the alignment of the part and the subjectivity of the operator when they set the datum and measure the final point.

bnt

For a low-tech method, could you get some templates made in a suitable material? They could have accurate cutouts covering the range of sizes you expect e.g. 299.8, 299.9, 300, 300.1 etc., and you'd just place them over the product to see which fit or not. I'm thinking a hard plastic, something that won't be affected by temperature changes.

squeekyduck

Thank you for everyones input.

We use templates at present for production op's. But at QA we need to be able to record the actual measurement as this information is kept on file and given to our customers if and when they request it.


The product in question is an angioplastic catheter with a stent. The below link will explain what it does, but most will be familiar (or maybe not!).

http://heartcarepc.com/handler.cfm?event=practice,template&cpid=12498


What we need to achieve is min handling of the balloon as excess handling induces premature failures in QA testing.

300mm is the biggest balloon lenght we will be manufacturing, at present the biggest balloon lenght we make is 220mm. The smallest is balloon lenght is 10mm.

At present, for small balloon lenghts the measuring technique is adequate as the balloon can be moved around under the microscope, but longer balloons lenghts are proving to be difficult.

Does anybody have any contacts/business recommendations for companies that deal in measuring solutions?

who_am_I?

I would recommend Inspection Equipment. they have an on-line catalogue at www.inspection.ie and a large showroom in Ballymount, Dublin 12.

Link to Vision Systems

link to Microscopes:

Turbulent Bill

squeekyduck wrote: »

The product in question is an angioplastic catheter with a stent. The below link will explain what it does, but most will be familiar (or maybe not!).

http://heartcarepc.com/handler.cfm?event=practice,template&cpid=12498


What we need to achieve is min handling of the balloon as excess handling induces premature failures in QA testing.

300mm is the biggest balloon lenght we will be manufacturing, at present the biggest balloon lenght we make is 220mm. The smallest is balloon lenght is 10mm.

At present, for small balloon lenghts the measuring technique is adequate as the balloon can be moved around under the microscope, but longer balloons lenghts are proving to be difficult.

Part of the issue is using the same absolute length tolerance for very different lengths. 0.1mm represents a 1% tolerance on a 10mm nominal length (very difficult, but maybe achieveable manually with very good fixturing), but only 0.033% on a 300mm length (impossible IMHO manually). Tolerances are usually given as percentages of nominal lengths for this reason, unless all the lengths are similar.

I know almost nothing about catheters, but given that they're flexible and hard to mount for measuring I'd imagine that the accuracy is much worse than the resolution. For example, the operator could be able to resolve the 0.1mm markings on the measurement tool, but the induced errors in mounting the catheter, keeping it straight etc. will dwarf this. It's pointless being able to measure something to an resolution of 0.1mm if you can only repeat the measurement to an accuracy of 0.5mm.

I'd suggest discussing with the design team what the tolerance drivers are (i.e., why is there a blanket 0.1mm tolerance), and specify your measurement equipment from this.