By Todd Miller, Manager of Product Marketing
The goal of any machining operation is to produce
accurate parts at the lowest cost, thereby maximizing profitability. The
traditional way to lower machining costs is to accelerate production rates with
more aggressive machining parameters, usually focusing on faster cutting
speeds. That approach, however, does not recognize significant cost factors
including the expense of scrapped parts and production downtime. Use the
following 5-step strategy to balance productivity and manufacturing costs.
1. Focus on the Costs You Can Control
Some elements of manufacturing costs are beyond
your control. Workpiece material type is dictated by the end use of the
machined component. Likewise, costs for machine tools, maintenance, and the
power to run them are basically fixed, usually involving ongoing payments. Your
strategy for increasing production economics, therefore, should focus on the variable
costs such as machining process elements like which cutting tools you use and the
parameters in which they are employed.
2. Find Optimal Parameters
There is a common misconception that simply
increasing cutting speeds will produce more parts per period of time and
thereby reduce manufacturing costs. While using higher cutting speeds can
increase production rates, it may also result in higher tooling and machine tool
costs. Finding optimal parameters is essential and requires a balance between reduced
cutting speeds and proportional increases in feed rate and depth of cut. The
ideal is to use the largest depth of cut possible to reduce the number of
cutting passes required and machining time. At the same time, maximize the feed
rate, albeit carefully so as not to negatively affect workpiece quality and
surface finish requirements. When a stable and reliable combination has been
reached, cutting speeds can be used for final calibration of the operation.
3. Reduce Machine Tool
Costs
Higher speeds initially drive down machine tool
costs because the machine tool is producing more parts per
period of time, therefore more revenue can be applied against its fixed cost. However,
as speeds rise beyond a certain point, machine tool costs begin to increase.
Tool life becomes so short that the decrease of the machine tool cost has a
smaller effect than the fast increasing costs of tooling and downtime for tool
changes. In addition, extremely high cutting speeds and very
aggressive machining parameters in some cases can add to machine tool costs for
maintenance and even result in downtime caused by unanticipated machine
failures.
4.
Follow A Model of Efficiency
American
mechanical engineer F.W. Taylor once developed a model for determining tool
life that
shows that for a given combination of depth of cut and
feed there is a certain window for cutting speeds where tool deterioration is
safe, predictable and controllable. When working in that window, it is possible
to quantify the relation between cutting speed, tool wear and tool life.
Following this model brings together cost efficiency and productivity and
provides a clear picture of what to aim for when defining the optimum cutting
speed for an operation.
5. Establish
a Stable Machining Process
The key to maintaining productivity and part
quality and avoiding scrap is establishing a stable machining process. Create
an optimum production environment by choosing the tool material, coating and
geometry best suited to the workpiece and operations at hand, and optimize the
machining CAM program, toolholding systems, and coolant application. Be sure to
integrate workhandling automation such as pallet or robotic part load/unload
systems into the process as well, because handling of raw and finished part
stock can consume significant amounts of machine downtime.
Want to learn more? Please contact me, and I’ll help you create a
balanced production strategy for your operations.
About the Author
Todd is the manager of
product marketing for Seco Tools, LLC. He oversees the product marketing team
and works with the company’s sales department to further enhance the customer
experience. He and his team also support product introductions while working
globally on new product testing to ensure customers gain access to the
industry’s most advanced tooling as quickly as possible. In his spare time,
Todd likes to bowl and cheer on the University of Michigan football team.
