Shop scenerio question

"vinny" on Tue, 24 Dec 2013 05:55:46 -0500 typed in alt.machines.cnc the following:

What is the cycle time? More specifically, can you load and start a second machine before the first one finishes? A third machine? Can you run two or more machines and catch any "out of tolerance operation" before it "Gets away"? Secondly, can you afford to duplicate any setup? Are there any specialize holding fixtures or tools which would need to be duplicated?

Where I worked, it basically was one guy per machine, as the runs were "short enough" that he could debur completed parts while the machine ran. Or the company figured that it was just as cost effective to have someone paying attention to the machine, no matter how long it took. It was not exactly as if he was standing around waiting for something to do.

-- pyotr filipivich "With Age comes Wisdom. Although more often, Age travels alone."

If the customer asks for the goods to be delivered yesterday then use all m achines at the same time (customer in in danger of missing a milestone/cont ract or you are making moulds). This is called throwing money at the proble m. If this extra money is paid by the customer then all is fine.

But the sane thing to do is to run them all on same machine, wasting manufa cturing resources because the sales department is not doing a good job (due date not realistic, no steady flow of work) is just covering a fuckup with another.

Sometimes we make parts 3-4 months before they are due to be delivered and that makes everyone happy, fill the gaps with a different type of work.

Sometimes we have to move jobs to another machine to do it on time or just to use idle resources but is a pita for a variety of reasons like rigidity, nc code compatibility, travel limits, lacking high speed mode, cost of too ling. This just adds unnecessary overheads therefore losing money.

DanP

I think the calculation has to involve setup time per machine vs. run time on the machine. If you have 3 weeks of work for one machine, and it takes several hours to set up, then it may make sense to run all 3 machines on the same job. If it takes days to set up and the run is only 2 days on one machine, you'd generally not run it on multiple machines.

Jon

20 years ago "B" was called daisy chaining. Today it's called lean manufacturing. "A" is a push system "B" is a pull system. "B" has many advantages. You are producing finished parts every day instead of 100's of op #1 today then op #2 tomorrow etc. What lean manufacturing calls WIP work in process. You don?t want piles of WIP stacked all over the shop, it isn't efficient. The other advantage of "B" is your process is proven at the last operation at the end of the day instead of 2 weeks later at op #10 when you find you have painted yourself into a corner and can't repeatably hold the part or tolerances because of an unseen problem at a subsequent operation. The people who fight it the most are lazy machinists who want to do a 4 hour set up then mentally coast while the job runs. "B" requires doing every setup in the process, not so much coasting. Many shops are still fighting lean manufacturing because of a condition called "wehavealwaysdoneitthiswayitis". Successful shops are finding pockets of profit by eliminating waste by increasing efficiency. I would recommend "B" wherever it is efficient to do so.

Lets say you run a certain kind of machine, mill, grinder, edm, lathe, whatever, just that they are all the same. Lets say you have 3 of the same machines at your disposal.

In that scenerio...in a job shop, or tooling shop, molds or dies, would you run...

A. Run each job in each machine individually, lowering setup time, and limiting setup mistakes with just 1 setup. B. Run each job in all three machines, shortening delivery date and lowering overall cost.

I realize each job is a special case, what I'm looking for is what is the norm where you are?

If you work somewhere that has one guy per machine with no automation....please dont reply.

Finished parts, the quickest way possible, is all that matters in any shop I'm familar with. It has been that way for at least a decade. If that takes several machines, fine but doing all OP1 then all OP2, is dead. You concentrate on finished parts. Nothing else matters except finished parts.

Any more stupid questions?

no, feed them to the next machine.

easy, inspect after each op.

any machinist will hate you for making him set up the same job twice, use t he guy to set it up and prove it the hand the job over to an apprentice and use the machinist for other jobs. or if there is no other job let the guy coast, you don't want to stress him too much.

setting the job takes time and has some degree of risk, don't do it if you can avoid it.

coasting is a low risk way of making money.

DanP