Do Not Turn Down That Tool Life Yet!
by Tim Murdock
Technical Specialist

When encountering problems with tooling, usually the first course of action is to turn down the tool life. I have heard terms such as “cut it in half” and “reduce the tool life by twenty five percent” when referring to tool life issues. This is not always the best action. In fact, this can lead to a greater amount of scrap parts. Let’s say your tool life is 1000 and each broken tool equals one scrap part. If you are breaking ten percent of your tools, this means for every ten tools you use, nine make life and one breaks causing a scrap part; so you get 9000 plus good parts and one scrap. If you turn the tool life down to 500 and you still break ten percent, now you get 5000 plus good parts and one scrap part which doubles your scrap. In this instance, turning up the tool life can actually reduce scrap. If you turned the tool life up to 2000 and you still break 10% of the tools, you can have one scrap part for every 18,000 plus parts. This short term solution can work when nothing else seem to help. 

The strategy for success in tooling issues can be dependent on engineering activities and the data available. Here’s what I suggest be done to solve tooling issues: First, we must talk to the machine operator. The machine’s operator usually has a better idea of what is happening than anybody else in the plant. Sometimes it is as simple as asking and you may find out that the part clamp has been broken for two days and maintenance has not fixed it. You now don’t have a tool issue; you have a maintenance issue that can be fixed and your scrap and tooling issues should go away. The second task is to collect data on all broken tools: When did the tool break, on what hole, what machine, what operator, coolant levels and concentration, what did the broken tool look like, etc. The third task is to collect the broken tools. This is useful because if you quarantine the broken tools and holders for evaluation, you can sometimes identify the cause because you have removed it from the machining process. 

The last stage is to eliminate causes until you have the true root cause. Ask yourself some questions such as; are there bird nests on the tools? Are there odd marks on the tool holder’s adapters? What hole is the tool breaking on? Graph when, during the tool life, the tool broke. The graph will give you the information you need to finally turn down the tool life. If eighty percent of the tools break at sixty five percent of their tool life, you need to turn down the tool life to sixty percent. This should only be a temporary situation because you need to continue to work on the root cause so you can implement a long term solution to protect your tooling cost per unit. So, turn down the tool life and continue to work on the solution.

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