Using stereolithography for low rate manufacturing of plastic covers 3

[KENAT]

Not sure this is the best forum but here goes.

We manufacture precision metrology tools, with run rates in the order of 50 or so per year, some slightly more, some a lot less. Historically the life cycles have been fairly long, 10 years or more but that seems to be reducing significantly.

On our latest designs we’ve been making use of plastic (the drawing I looked up said polyurethane with no grade specified sorry this is a bit vague) to improve the aesthetic appeal of our product. While the individual covers vary in size think of things from the size of a food processor or sewing machine (cause that’s what the first product of ours that used plastic covers looks a bit like to me) up to a large cash register or maybe 21” CRT size.

To me a major issue on this is the cost and timescale involved with making the molds for these parts. Our suppliers typically make a temporary silicon mold for the first 10-20 to prove out the design etc and then we go to an Aluminium mold. The silicon molds are typically several thousand $ while the aluminum molds are several tens of thousands. The molds take weeks or even months to get made too which is a problem as we’re trying to reduce our development cycle.

In order to reduce cost (at least up front cost) and speed development I wonder if these covers would be a good candidate for some kind of ‘rapid manufacturing process’ like STEREOLITHOGRAPHY or SELECTIVE LASER SINTERING.

I had a quick search on the web and this site (thread404-10501 for instance) but had trouble separating the relevant information from the various patent claims and minimally informative articles etc.

Any advice on the current ‘state of the art’, relative costs, potential sources or information or even vendors etc. would be appreciated. I’ve dealt with stereo lithography parts before but they were far to fragile even for our relatively delicate instruments.

Thanks,


KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

What is Engineering anyway: faq1088-1484

 

[HDS]

The design process for anything that needs a mold is expensive and time consuming. That is where a skilled engineering can justify his pay. Maybe you should lean on the rapid prototypes for the prototyping. Then you can do the iterations easier and move to a tooling based process for production. Then you could get your hands on a few RP parts to get a feel for them. You are allready using the advantage of the RIM process that you can start with Silicon molds. Maybe you need to stay in silicon for production.

You should be able to pressure form (a type of thermoforming) the parts.

Those parts might be injection molded by Protomold for the same price (or less) as rim. You can get a quote off their webpage. It also has graphical feedback of the draft and other moldability issues.

With any process some vendors are more competitive in time and development support than others.

Your cad software has some tools that help like draft checking.

All of those holes in the sides of walls and ribs are expensive.

Bayer has a good rim design guide.

 

[KENAT]

I'm starting to think that the fundamental problem with the 'covers' on the right was that they were an after thought and that the people that designed them initially didn't put any thought into manufacturing process.

I completely re-did the bottom right cover but was hamstrung by marketing/aesthetics concerns initially and a colleague who seemed unable to understand the process.

The covers on the left are still in development by completely different person and appear to have been included etc from the start. I wonder if that's a big chunk of the difference. I haven't been able to find the guy for a week or two but did notic he has what appear to be stereo lith parts on his desk already.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

What is Engineering anyway: faq1088-1484