It’s been said more than once that great fixtures are the secret to profitability for machine shops. But that’s not always true. There’s the shops that leave a couple of vises permanently mounted to the table, set their work offsets to the corner of a fixed jaw, and swear by that. Not much of a fixture in that, yet many of these shops seem to do just fine. Sometimes a fixture pays handsomely, while other times it is an additional expense that won’t pay for itself. How do you tell whether a fixture makes good economic sense or not?
It turns out that it is tragically knowable whether spending time to create a fixture makes sense or not. We’ve just added a Fixture Calculator to G-Wizard Estimator that’s designed to help you answer exactly that question–whether a particular fixture makes sense or not. All you have to do is answer a few question and it cranks out the answer for you. Here’s what the Fixture Calculator looks like:
The Fixture Calculator from G-Wizard Estimator…
The idea is to fill out some basically information on two fixturing alternatives. In this case, we’re comparing a couple of vises to a custom fixture plate with toe clamps that will hold 10 parts. So, the vises can do 2 parts per lot and the fixture plate does 10. Here’s the basic information that has to be filled in:
– Description: Just so we can keep the two options straight.
– Build Time: How long to build the fixture? In this case, we already had the two vises so there is no build time.
– Setup Fixture: How long will it take to setup the fixture on the machine?
– Unload/Load: Time to unload the parts in the fixture and load new material for the next run.
– Parts per Run: How many parts will the setup take per run?
– Part Run Time: How long to run a single part?
Lastly, we need to know how many total parts are to be made. In this case, I picked 1200 because it was the number where the two came out equal in terms of total time.
Of course there are some things to think about:
– The fixture saves quite a lot of Operator load time–360 minutes for this example. Can you do something valuable with that time? You may prefer a fixture that doesn’t yield a Total Time Savings just because it frees up an Operator to do something else valuable enough to offset the Total Time Cost.
– The fixture saves Operator time, but it burns more skilled machinist time because the fixture has to be made. We’ve budgeted 6 hours for that in the example. You’ll have to decide whether the Operator Load Time Savings is worth spending some of the more skilled machinist’s time. In this case, we spend 6 hours of machinist time to save 6 hours of operator time. That might not be the best trade off.
– Is the fixture an investment in the future? Will the customer reorder more of the same parts? Can the fixture be re-purposed easily for similar parts? Perhaps a nice vacuum fixture that will see a lot of use is worth investing in even if it doesn’t make sense for the particular job it’ll be used on first.
By playing with some different scenarios, you can get an idea pretty quickly of whether it will make sense on a particular job to take time out and build a fixture.
If you’d like to try the Fixture Calculator, you’ll need to get G-Wizard Estimator. While it is in Beta, it’s free for anyone who can access G-Wizard Calculator either via Trial or Subscription. If you haven’t tried our G-Wizard Calculator Software, by all means give it a test drive. You’re in for a real treat as our many customers will tell you.
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