How do you handle heat and thermal expansion when CNC machining steel?

When drilling holes the point angle will determine % of tool contact to your work piece. In case of a 165 degree angle much more engagement is made increasing load. Thus a 118 degree angle point will reduce it. Knowing your materials and composition will help you best choose tool design needed. This works same as choosing a 30 degree flute helix for softer materials such as aluminum . Chip breakers on point and flutes are a popular choice to make smaller chips while avoiding the "stringy" buildup that will drastically reduce the life of your tool and require added machine tending. The function of cutting tool geometry is a widely overlooked necessity to optimize any machining operation.

By understanding feeds and speeds and using the correct insert for the type of material. Flood coolant at the correct mixture ratio is a positive addition also

Machine condition is most important when attempting any high precision operation. Knowing that your ballscrews, linear guides, box ways are all in good condition with proper lubrication can avoid the variable least noted. The machine condition along with spindle health will add to vibration and chip loads not calculated. Premature tool wear in a production environment is caused by this factor alone. As you ran xx amount of parts per tool and under same conditions now run less, then this is a time to look at the machine. Working with application engineers in cutting tools we have identified machine problems and with a proper intervention have kept that tool running as intended. Preventive Maintenance and periodical evaluation is key .

A higher feed rate generates a thicker chip which in turn helps in carrying the heat away from the cutting zone. A high cutting speed increases the temperature at the cutting edge which will influence the thermal expansion of the workpiece. Using adequate coolant is the solution. Use coolant through insert holders that will direct the coolant at the cutting zone.

High pressure coolant systems used on through spindle ready machines can give you a double edged sword effect. Rotary unions allow for coolant to pass through the TSC system and 1 : Evacuate chips quickly and 2 : Keep temperatures at bay. Many systems for all applications exist . Lathe , Swiss turn, Machining centers can all be piped with an external system to improve your process and at most times make cost in time and tooling efficient.

Most machines will have some form of chilling system for the multiple axis and spindle of the machine. Temperatures must be maintained between 68-72 degrees F. This temperature range is the same that is used for calibrating and certifying measuring equipment. Ultimately the effects thermal expansion will have in your shop will be determined by the tolerances that need to be held.