As Jim and Jason always say on the MakingChips Podcast, “If you’re not making chips, you’re not making money!” We all know it’s true, yet few shops have formal systems for increasing their spindle uptime.
An important component to fixing this is to reduce the downtime between jobs – the time between when you finish the last part on one job and when you make your first good part and start running the next job on that same machine.
Here are a few general things that need to happen when you finish a job:
- Remove the fixtures off the machine, or take out your softjaws, etc. (unless you have modular tooling that will be used on the next job also.)
- Take any cutting tools out of the machine that you won’t be using on the next job.
- Clean off the bed or table.
- Download your programs (and save them) or delete them off the machine.
- Sign off that you’ve finished that operation on paper or in your ERP system.
- Wheel the cart or pallet to where it’s going next.
This process is generally pretty fast. If you’re lucky enough to be on a horizontal, you might even be able to change out your fixturing while your other pallet is still running. Or, maybe you’re using universal tooling so changing over doesn’t require taking out your fixture, or it only takes seconds.
Generally, the next step of the process is getting your new job set-up on the machine. This is where most of the savings can be had and where many companies need a lot of help.
Here is how this process often looks:
- The machinist goes to find out what is next on the machine and get the paper job packet.
- They go and look for material and hopefully find the right stuff.
- They start collecting some cutting tools and holders from the setup sheet which match the general description of what they are looking for (e.g. ½” EM – but may not be exactly the right tool at all).
- They try to find the fixtures needed for the job which may be lost, damaged, or misplaced and bring these things over to the machine.
- They review some incomplete set-up instructions on an old set-up sheet or try to remember it from last time.
- They load tools into the machine, and manually touch off the tools in the machine or with a machine probe.
- They mount fixtures or vices. (Hopefully, the fixtures are dialed in with pins or use zero-point fixtures. If not, then they need to find a dial indicator and dial in the fixtures or vises.)
- They upload the program into the machine controller.
- They wander away from the machine several times to go find things they didn’t collect at first.
- They put some raw stock into the fixture or vise.
- They turn the feed and rapids down, maybe put it on a single block, and show “distance to go” on the controller.
- They slowly step through the program and prove it out, being careful to not crash until the entire part is machined.
- They go find measuring instruments to check the part.
- They check the resulting part against a paper drawing which may be dirty, ripped, old-rev, and check a bunch of dimensions to see if they think the part is good.
- Once they have a part they think is good (which might take several tries), they submit the part to the QC department and wait (sometimes a long time).
- Once they have received approval from QC, then they can start making parts. This is when the timer stops, and the spindle is “Up” again.
As you can see, this lengthy process and can contribute to vast amounts of downtime where you aren’t “Making Chips”. Often, the things they are looking for aren’t there, can’t be found, or aren’t ready yet. It can go south quickly, and setups can take many hours or even days. With so much lost opportunity for revenue and throughput, there must be a better way.
With a little forethought, some planning, and a checklist, you can dramatically reduce this downtime between jobs.
At Pro CNC, we studied this problem for years in our own shop. We applied lean principles, concepts from franchise businesses, and decades of our own experience and those of our employees, and built the best practices into ProShop, the software we developed.
ProShop is now a commercial software product providing a comprehensive web-based and paperless shop management system for small to medium manufacturing companies.
At the end of the day, being in business comes down to profits. Profits enable you to grow and invest in your company, attract and retain the best talent, and outperform your competition. With manual processes or shop software that relies on paper-based processes, collecting data about job costs is either impossible, tedious or too expensive. So it doesn't get done. With detailed costing, shops can significantly boost profits by making the right decisions.
Here are a few strategies, based on our research, to help any machine shop reduce downtime and make more chips:
- Analyze all setup steps for each job and categorize them into “internal” and “external”. Internal means you have to be at the machine to do it; external means you can do it in advance without using the machine.
- Do all external steps at least one day in advance of the job hitting the machine. Pull everything onto a job cart or queuing area.
- Ensure the material is available and prep or stage it near the machine.
- Pull all your tools from inventory – make sure you have them and won’t need to overnight any tools.
- Load tools into holders and do offline presetting if possible.
- Collect all the inspection gages you will need for inspection.
- Confirm that the programs or proven G-Code are ready and queued up in the proper location.
- Make sure all fixtures are available.
- Pull any other ancillary items like Scotchbrite, packaging materials, etc.
- When the last job finishes, quickly clear it from the machine and wheel over your new job, with all the prepped items ready to go. The goal is to have the machinist setup the job without having to leave the machine.
- Develop a simple checklist for people to follow to ensure they’ve done all the steps. Even surgeons dramatically reduce the risk of death from complications when they use a checklist before surgery, so they can definitely help your machinists.
Use it at your Machine Shop!
How to Reduce Downtime in any Machine Shop and Make More Chips
With these simple tips, shops can improve the number of hours their spindles are turning each day, and make it easier to always be Making Chips!
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