Working with CNC Machine Tools

CNC machining has the ability to run thousands of parts smoothly and accurately with the push of a button. But many complex components must work together to produce a workpiece of consistent quality without costly downtime. The smallest fraction of measurement or timing error can bring production to a full stop. Tooling is one of those components with great significance. Here we look at addressing common problems working with CNC machine tools.

Hardware

Tool Selection

Problems with material finishes are often the result of tool choice. Tool size and material composition is an important choice depending on the material and the finish requirement of the workpiece. Incorrect tool choice can cause uneven finish, especially in corners. This will shorten the life of the tool through extensive wear. A blunt tool will also cause further finish problems in production.

The improper feed speed ratio is another tool-related problem. Both the workpiece material and cutter tool material determine the rate of speed. Knowledge in metallurgy is necessary when specifications and tolerances must be verified against material hardness and tensile strength.

Clamping

Clamping of the workpiece is important in setup and production. The tool must also be securely fitted into the chuck, and the chuck must be securely fastened in the machine fitting. Lubrication, hydraulics, and electrical connections are equally important to the proper operation of the chuck.

As above, the quality of the workpiece finish will suffer due to vibration or shifting. A loose-fitting could cause damage to the workpiece, the tool, the CNC machine, or even the operator.

Maintenance

One of the key roles of the operator to listen and watch for signs of vibration and heat. Heat can result in distortion of materials. Some amount of vibration and heat are normal parts of machining through friction, specifically with metals. There are key maintenance steps to ensure neither builds up too high. After each production run both the machine and tools need to be cleared of dirt and debris as well as regular maintenance to check:

Coolant levels

Air production

Electrical wires and solenoids

Air filters

Lubricants

The Human Factor

CNC machines are highly sensitive equipment able to produce the most finite movements. Many production errors are a result of incorrect G codes in programming or manual setup of the machine.

Understanding the basics of machining is critical to translate into programming.  Comprehensive user manuals, training, and ongoing support should not be dismissed from the tool and machine suppliers. Skill and experience from operators on the shop floor can also help train new operators. Constant growth and change in CNC manufacturing require a new approach for machinists. A well-rounded machinist will possess effective visualization for design, hardware and machine knowledge, as well as programming skills.

Simulations are also imperative to confirm the geometrics of the design before beginning the machining process. Damage to tools, waste material, and shop downtime result when programming doesn’t translate into the machine operation.

Although robotics and IoT are creating machines that seem to have their own intelligence, knowledgeable staff is still very necessary in a CNC machine shop. Eyes, ears, and common sense are important skills to check finish quality, vibration, and detect problems in automated processes, like feed rates or automatic tool changers.

Incorporating careful design, regular maintenance, and understanding the value of relationships between staff and manufacturers make key differences in the effectiveness of tool function in your CNC machine shop. Collaboration between people and automated equipment also eliminates common problems working with CNC machine tools, resulting in increased efficiencies and profits.