Identical parts with different material compositions

I'm hoping someone won't mind brainstorming a bit. We will be looking at manufacturing parts that look identical but have different material compositions. Unfortunately the quantities are too low to justify separate manufacturing cells for each. Some of the parts are smaller, approximately 1 inch in length.

We use routing packages and pallet tags but are considering rubber stamping individual parts to ensure they can't be accidentally mixed. Anyone have some experience with traceability and segregation like this?

 

We do this a lot -- same part, different materials. A couple of things to watch for. Certainly, if you can mark the individual parts at the time of production that is ideal. A simple color coding with a sharpie can work. If you can't do it at the production station, then keeping things separate and workstations clean is important. Make sure all of the old part are "gone" before you start the new part. You might also invest in a material tester (I want to say they use ultrasonic sound waves) and add a test to your process downstream. Good luck.

 

Just thinking out loud...

Are the two materials different enough to reliably measure a difference by weight?

I have two identical looking white plates stored next to each other with no issue. Only the bins are marked. The density of one is 4g/cc, the other is 6g/cc...a simple scale (2 feet away) has no issue telling them apart.
Most operators can tell the difference as soon as they pick them up due to the weight difference.

 

Thanks for all the ideas, they definitely help. We might go with color coded sharpies and just a quick swipe on each part as they are machined. Then we can use the same color code on the traveler/router paperwork, pallets, and containers. Maybe even color coded tape and/or wrap on the pallets too. Unfortunately the weight is the same, but that's a great point to keep in mind for future stuff.

 

First thing I would look at is making absolutely sure that you actually need 2 different parts. Is the difference in material properties significant? Where do the requirements for different materials come from, and why? Is it still current?

Could be an opportunity for improvement.

 

A lot of times, the same part in different materials are used for different environments. The cheap people use plated steel. More corrosive applications use stainless. And the absolutely, positively, can't have an issue use ultra expensive alloys.

 

I guess we won't know unless James will tell us...?

 

Unfortunately that gets into customer intellectual property. But they are using multiple compositions for specific reasons that can't be avoided.

 

Fair enough.

Another thing I would look at, if CNC is involved, is adding a minor feature with one of the tools already involved, e.g. a harmless dimple that can be created with the tip of a drill (you have to make sure that the design is not adversely affected). This could be another (more consistent?) layer on top of human actions, and is more permanent. When investigated complaints where the constituent material is important, it's very handy to be able to easily tell what material was employed, months and years after production.

 

Color coded shapes can work (red boxes, blue circles, .....)

 

Great idea, we are a CNC shop. Good heads up on color blindness too. Shapes are a great point too.