Are you nuts?

This letter is in response to the October 2004 MODERN CASTING editorial "Are You Nuts?"

I find the logic in proclaiming that all foundries should be using simulation faulty in a couple of areas. First, it was indicated that all sorts of time and money will be saved in not having to rework tooling beside the cost of scrap. What defects do you believe simulation will prevent? The defect most commonly talked about is shrink. For an iron metalcasting facility, which I have records going back some way, less than 1/3 of 1% of their production was to shrink in 1992--long before they did anything with simulation. That facility now has the capability to do simulation, and although they don't use it on every new job, they use it when they expect a problem, in the last fiscal year that just ended, their scrap from shrink defects was all the way down to 0.23% of their production. Other defects that could be reduced with simulation also have not dropped significantly.

The other area that I think may have an erroneous perception is the typical size of orders dealt with in many of the smaller operations. We typically hear from the high-volume producers or the producers of very large castings. In both of those cases, I agree with you that they'd be nuts not to use simulation. However, there's a whole other world of foundries out there that deals with small sizes and numbers of castings. Quotes will likely give price breaks at 10, 50 and 100 pieces. Let's take a theoretical look at a new order of a 10-lb. casting

Assume were' going to have the CAD file. That speeds up the process, but someone still has to put in the first estimate of the gating and risering, right? My best guess is that under ideal situations, an experienced simulation operator wouldn't be able to do more than two jobs per day. So, we have four man-hours into simulation. How much is that worth? For the sake of argument, let's say $50/hr. including overhead. We would have a cost of $200 before we start to make the pattern. What are you going to do with that cost? Are you going to recoup your costs on the first run? If so, that means on the 10 quantity, we are adding $2/lb. to the price of the casting, on the 50, we are adding 40 cents, and on the 100, 20 cents.

Please, don't misunderstand. I do think in Some situations metalcasters would be foolish not to use simulation, but I challenge anyone to show me the "true time or cost analysis" that was done to justify saying that every facility should be using simulation.

If a foundry is giving enough customers what they want and is making money doing it, they should be around lot a long time.

Roy Lobenhofer

President

Lobenhofer Consulting Inc.

Mount Prospect, Ill.