Author: Paul Van Metre
In a machine shop, you’re only making money when your spindles are cutting chips. Any time a machine is sitting idle, it’s a liability, not an asset. It’s costing you money, not making you money. So any shop’s priority should be to keep the spindles turning as often as possible. Despite the importance of this, far too many shops don’t put simple processes in place to keep those spindles turning as often as possible. There are numerous ways to increase spindle uptime, and one important way is by using offline tool presetters.
When making precision machined parts, one of the most important variables is knowing the length (and diameter) of your cutting tools relative to each other and to the machine and program coordinate system – and therefore your raw material. The traditional way to establish these measurements is to load the tool/holder combination into the machine and touch off the length of the tool to a vice surface, or some other known datum. People use everything from a piece of paper, or brass shim stock, dowel pin, to inexpensive contact based measuring devices. While these methods seem very inexpensive, they are in fact the most expensive way possible to measure tools, for two main reasons:
- They reduce the amount of time the machine is cutting chips.
- They aren’t very accurate, contributing to low first part yield.
Let’s explore these a bit further. As already mentioned, a machine is only making money when it’s cutting chips. In a typical VMC, in a typical job shop, the average spindle uptime is only around 25% as it is. When setting up a new job, any time that detracts from getting your first good part out of the machine is considered setup time, and isn’t making you money. If a typical manually set tool takes 2 minutes to measure, and the typical part takes 20 tools, then 40 minutes is wasted making manual tool length measurements. If the typical machine is changed over twice per day, that’s over an hour of time that you aren’t cutting chips and making money. Rounding down, in a shop with 10 machines, that’s 10 hours per day, or 2000 hours per year if you only work 5 days a week. At a conservative shop rate of $75/hr, that’s $150,000 of potential revenue that will never be realized because your spindles aren’t turning. And that is only considering the time spent to touch off tools. Next comes the prove-out process which is potentially much longer. When tools are not accurately measured, the prove-out process and dialing in your tools to get a first good part can take significantly longer, wasting time and material. And the lower volumes your jobs are, the more crucial it is to make this process as short as possible. Assuming your setup takes 25% longer with poorly measured tools, and the average setup takes 2 hours, there is another 30 minutes per job wasted which is another $150k in down time per year. Now, those numbers are very generic and the situation isn’t the same in all shops. Some shops run the same job for days or weeks at a time, and some jobs take far fewer tools than others, and some have in-machine tool probes which are faster, so the effect is less. But, while machines with in-machine tool probes are typically faster and more accurate than manually setting the tools machine-side, they still have to be set while the machine is sitting idle not making chips. That is another reason off-line presetting can help drive down costs. Regardless of the specific numbers in your shop, the cost of in-machine tool setting is significant compared to the cost of implementing offline tool presetting.
The cost of offline presetters varies enormously. An entry level machine can cost under $10,000 and more automated machines with lots of bells and whistles, can cost as much as a CNC machine. And often the software used to manage them is a considerable percentage of the cost. What type of presetter makes sense for a shop depends on many factors, including the volume of tool setting that is needed, the tolerances being held on the parts, and many others. Your local representative, and the internet can provide you with many options to consider.
How does ProShop help with this?
ProShop has modules to help manage both the entire tooling library for consumable tooling, and tool assemblies that we call RTAs or Rotating Tool Assemblies. When a job is won, the tooling demand is reflected in the purchasing module to be purchased if current inventory isn’t sufficient to cover the demand. Once the job is ready to be kitted (ideally before the machine is ready), employees can pull the required tools from inventory and transfer them digitally to a tool caddy, along with the tool length offsets that have been measured with an offline tool presetter via the Workcells module. When a tool is measured in the presetter, a serial output can be sent into ProShop where the length is recorded. Once all the tools for a job have been measured and recorded, the preset tools are ready to be loaded into the CNC machine, ProShop can generate an offset file that can be transferred into the machine control. Having the offsets loaded digitally dramatically reduces data entry time and the (extremely) high potential for manual typing errors which can lead to catastrophic results.
Building this workflow directly into ProShop, rather than working with spreadsheets or different off the shelf software packages offers numerous advantages. Clients who embrace this workflow have seen significant improvements in setup time reduction (often 25% or more), reduced spindle down time, reductions in UPS Red shipping charges, and much more.
If you realize that your shop spends too much time with the spindles sitting idle, we encourage you to research tool presetters. And we’d be very happy to talk with you to see if ProShop can be a part of that solution to keep those spindles turning more often.