Cut waste at the machine tool

Lean manufacturing principles are based on the concept of eliminating waste. Lean experts have categorized waste in various ways, such as over-processing and inventory. Waste is generally anything that does not add value to a product.

Many shops do not practice lean manufacturing but still work to eliminate waste. It is easy for machinists, programmers and engineers to understand why reducing cycle times, increasing tool life and boosting spindle utilization are important to improve the bottom lines of organizations.

Cutting faster is often the default method for eliminating waste at a machine shop. Machinists and programmers are usually keen to try the latest high-performance cutting tools or programming techniques aimed at reducing cycle times. Evidence of this can be seen in the popularity of tools and approaches like trochoidal milling, variable-helix endmills and high-feed inserts.

Machine tool builders and cutting tool manufacturers will continue to bring technological innovations aimed at improving machining processes and eliminating waste. However, demand for improvement always will outpace advances in technology, so machine shops need to find other ways to eliminate waste.

Keep Chips Flying

One of the most effective ways to reduce costs and improve bottom lines is by eliminating noncutting time. It is amazing how much time is wasted at a machine tool with activities that do not add value to the part being produced.

While at a previous employer, our team worked to eliminate noncutting time by addressing everything that kept a machine from making chips. In the end, we improved productivity so much that we were able to reduce cutting speeds and feed rates to save additional costs by extending tool life. To accomplish this gain, we improved our inspection processes, enhanced tool life management involving redundant tools and added part probing to eliminate manual setup. The result was a first-year savings of $300,000.

Single-minute exchange of die is a Toyota Production System concept that many shops have adopted. The idea is to change fixtures and tools as fast as possible because the time spent changing does not add value to a part. For small shops, implementing this concept can require a cultural shift away from traditional methods like indicating parts or “dialing in fixtures” and toward developing more proactive fixture designs that utilize subplates and similar quick-change devices, thereby reducing setup times and returning machines to production sooner.

Mitsubishi Hitachi Power Systems Americas specified pallet changers for its horizontal boring mills and recovered the added expense during the first year that the machines were in operation. Image courtesy of C. Tate