HOW TO DETERMINE THE REAL COST OF YOUR END MILL

A higher priced tool can ultimately prove to cost much less than its lower priced counterpart. The true cost is found after its performance is quantified.

More often than not, the first question a mold maker asks when presented with an end mill is, “How much does this tool cost?” For this, there is really only one answer, “I can tell you the price, but I cannot tell you the cost until you run the tool.”

A higher priced tool can ultimately prove to cost much less than its lower priced counterpart. For example, if a tool that is priced three times higher performs five times better, its actual cost is 40 percent less than the less expensive tool. Certainly, it is true that the premium product will not always provide five times the performance, but what is equally true is that the price is not always three times more. Often the price difference is smaller, but the principle remains the same. The difficulty is to accurately quantify a tools performance.

While it is possible, in theory, to establish a range of performance for a particular tool, actual performance can vary based on a multitude of variables including the machine tool,  material, toolholding, workholding and the coolant/lubricant used. This means that the only accurate method to evaluate a tools performance is through testing under real world conditions, in the particular operation in which the tool will be applied.

Quantifying a tools performance, particularly in a high-volume mass production environment is a fairly straightforward exercise.  The performance of a cutting tool can be measured against either time in the cut, or the quantity of parts generated. However, in a lower volume setting like moldmaking, wherein the life span of one tool can extend through several different applications or repeated applications that occur on an irregular basis, attaining an accurate assessment on tool life and performance can require a greater level of commitment and effort, or even the implementation of specific new technology, such as tool holders equipped with radio frequency identification (RFID) technology to monitor a tools usage.

It is common for tooling companies to offer test programs. These programs are symbiotic arrangements in which the supplier gains an opportunity to showcase new product while the customer gains the opportunity to enhance the manufacturing process. Enhancements may go beyond simply increasing tool life; the savings achieved by minimizing tool changes a down time should also be considered. In addition, the knowledge that can be gained through testing can be invaluable; new ideas, methods or strategies can be realized, process steps can combined or eliminated through exposure to new and developing cutting tool technologies.

For instance, the following example illustrates how important this testing process is.

Application engineers demonstrate to a customer how the right end mill, even when higher priced, provides significant savings over a less expensive option. In a recent application using a premium end mill, the actual cost of machining a single part was reduced by 50 percent. Because the tool included diamond polished flutes, coolant through the tool and proprietary edge geometry, a 22 percent increase in cutting speed and an 85 percent increase in feed rate were realized. As a result, the premium priced tool was able to complete 41 parts in the same time as the competitive tool completed 9 parts. When calculated with a constant tool life and machine cost per hour, the cost per part was 51 percent less, even though the premium tool was twice the price. In fact, in order to mach this level of overall performance, the “cheaper” tool would have to cost 70 percent less.

Now how much does your tool cost?