By Manfred Lenz, Manager – Drilling Products, NAFTA
Maximum productivity and profitability in machining operations hinge on two key components of machine tool utilization. The first is to maximize the amount of time the machine is available to actually cut metal. The second, which is often neglected, is to then make the most productive use of that time.
Maximize available time
Machines are on the shop floor 8,760 hours (365 days) a year, but their productive availability is much less than that. For instance, a year of five-day, single-shift workweeks, and taking into account time lost to holidays and other interruptions, equates to approximately 1,300 or 1,400 hours of actual available machine time. However, programming and setup further consume a portion of that time.
To shorten a machine’s non-cut time as much as possible:
• Use strategies such as offline programming and modular setups
• Streamline tool handling with tool magazines and automatic tool changers
• Quickly load and unload workpieces with robotic work handling and/or pallet changers
Make efficient use of time
Once available to cut time is maximized, manufacturers must use that time efficiently, which means to produce as many parts as possible and at the lowest cost. To accomplish this, machines, while in the cut, should run at their full potential/capabilities but without exceeding safe limitations.
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| Average Time Spendings on a Machine Tool |
Keep in mind that some elements of the machining process are unchangeable. A component’s final application determines the raw material from which it’s made, and the material’s machinability, in turn, dictates basic cutting parameters. For example, the poor thermal conductivity of titanium alloys requires that machines run at lower cutting speeds and feedrates to minimize heat buildup.
Machine tool capabilities are also a given, because changing the machine is rarely an immediate option. Manufacturers recognize these factors when estimating production costs. However, significant differences between estimated and actual costs can result from inaccurate evaluation of machine tool characteristics and the application of cutting parameters that are impossible to sustain.
There are some common strategies applicable to all machining operations for establishing initial cutting parameters that will contribute to efficient machine use.
• Select cutting tools with substrate material, coatings and edge geometries that are best suited for the workpiece materials and intended machining operations.
• Apply the tool’s recommended minimum cutting speeds to prevent tool breakage, ensure proper chip formation and limit heat generation.
• Increase feedrates and depths of cut as high as possible without compromising workpiece surface finish.
• Recognize the power and stability characteristics of the machine tool.
By concentrating on maximizing machine tool availability and making the most of that time, you can increase both productivity and profitability in your machining operations. For more ideas on how to effectively manage your tools, please feel free to contact me.
About the Author
Manfred has been with Seco for more than 16 years. In his current role as drilling product manager, he is responsible for every aspect of the company’s drilling products in North America. He works closely with global R&D on new innovations to ensure they meet the market’s tough manufacturing demands. Manfred also supports the Seco sales force by providing them with technical information and cost saving solutions that bring value to customers. In his spare time, he enjoys boating, bowling and golfing.
