How To Avoid Material Damage In CNC Machining Production

 

CNC machining has gained widespread popularity in the production industry owing to its precision and effectiveness. Nevertheless, despite its state-of-the-art technology, CNC machining encounters cutting challenges that can harm tools and materials. It is vital to comprehend these issues to decrease downtime and prevent damage to workpieces or tools. This article will explore the three cutting challenges that can result in material destruction and tool deformation during CNC machining.

Ensuring the machining defects due to chips

The presence of chips can be an indication of possible machining defects.

• Excessive chips in a machining area and chips wrapping around equipment
• Fragments getting caught when modifying the workpiece
• Unexpected cutting tool breakage may indicate the presence of chips causing defects
• Frequent stops or unplanned downtime during the machining process
• Drill Destruction due to chip buildup during drilling.

Prevention

• Use cutting tools that are sharp and properly maintained to reduce the force required for cutting, thus preventing the formation of chips.
• Utilize appropriate cutting speeds and feed rates to avoid tool rubbing and heat generation, leading to chip formation. Cutting too quickly can also impede material removal due to inadequate removal rates.
• Implement chip breakers and removal tools to facilitate efficient chip management.

Defect by Chatter

Chatter, an irregular shaking that arises during machining, can be categorized into two types: self-excited chattering and forced chattering based on the origin of the vibration. Forced chattering results from external forces acting on the Machining equipment, including Instability in the cutting tool and workpiece, an unstable machine foundation, imprecise work holding, weak rigidity of the machining tool, and inaccurate posting. Chatter can lead to a complete batch of faulty work pieces.

Several factors can support forced chattering, such as:

• Machine spindle: If the Mandrel of the machine is not operating at the correct speed or is imbalanced, it can generate vibrations that result in chattering.
• Tool holder: Chattering can be caused by vibrations from an incorrectly designed or worn tool holder.
• Cutting conditions: Chattering can be exacerbated by high feed rates, high cutting speeds, and deep depths of cut.
• Workpiece properties: Compared to softer materials, hard and brittle workpiece materials are more susceptible to chattering.

The following tactics can be useful to minimize or eradicate chattering:

• The machine spindle should be balanceable.
• Use a quality tool holder
• Consider using a cutting tool with a bigger radius.
• Also, consider using a stronger cutting tool material.
• Besides, consider using a cutting fluid during the machining process.
• Consider using a tool holder with improved chatter-damping capabilities
• Use a more stable & robust machine
• Using a workpiece material with lower hardness.
• Using a controller for suppressing chatter.

Self-excited chattering is a machining phenomenon wherein the cutting tool vibrates wildly, resulting in diminished surface finish quality and heightened tool wear. This type of vibration is considered self-excited because it results from the interaction between the workpiece & cutting tool rather than an outside source.

Several factors can participate in self-excite chattering, such as:

• Cutting tool geometry: Tool geometry, including a small radius, can increase the tool’s susceptibility to chattering.
• Cutting conditions: Chattering can be amplified by high feed rates, high cutting speeds, and deep depths of cut.
• Machine conditions: Vibrations that cause chattering can result from loose & worn mechanical components.
• Workpiece properties: Compared to softer materials, hard or brittle workpiece materials are more susceptible to chattering.

The following techniques can be useful to reduce and eliminate chattering:

• Reduce cutting speed or feed rate
• Use cutting equipment with a larger radius
• We recommend the utilization of a stronger cutting tool material.
• A cutting fluid is also useful.
• Consider using a tool holder with chatter-damping capabilities.
• Moreover, consider using a machine with greater stability and robustness.
• Besides, also consider using a softer workpiece material.
• Implement a chatter suppression controller.

Chattering not only results in subpar machining but can also cause harm to the machine. Defects associated with chattering in CNC machining production comprise workpiece deformation, inaccurate dimensions, tool breakage, low-quality surface finish, safety hazards, and more. Thus, immediate measures are necessary to prevent this issue.

Ensuring the machining defects due to chattering

The following signs may indicate the presence of machining defects generated by chattering:

• During the machining process, if you notice a prominent vibration accompanied by a loud and rhythmic noise, it could indicate a problem.
• Deterioration in the surface quality of machined components.
• Damage to machine or tools
• Minimize machining accuracy.
• The workpiece exhibits surface defects, which may include scratches or pitting.

Prevention

• Use tools with a Positive cutting angle to reduce cutting forces and prevent chattering.
• Make sure the CNC machine is placed on a stable foundation.
• Check for any looseness and play in the setup.
• Maintain proper tool alignment.
• Consider using tools with the chamfer or rounded edge to absorb vibrations and reduce the hazard of chattering.

Defects by Chipping

Chipping removes material from a workpiece in minor chips or fragments, which occurs on the cutting edge of a cutting tool. It commonly occurs during cutting work, but it is crucial to detect it early because even minor chippings can cause unexpected machine stops & various harms in CNC machining operations.

Defects caused by chipping can be attributed to several fundamental reasons, such as inadequate high cutting forces, tool strength, wrong tool path or geometry, and the firmness of the workpiece.

Ensuring the machining defects due to chipping

The following signs indicate the potential occurrence of manufacturing flaws caused by chipping.

• The following signs may indicate the presence of machining defects caused by chipping:
• Frequent stopping or unexpected downtime during the CNC machining production.
• An uneven, rough surface finishes with a flat, satin-like shape.
• Extra wear on cutting equipment.
• Poor productivity and low machining cycle time.

Prevention:

• Regularly maintain and sharpen cutting tools to ensure they are in good condition and can produce clean cuts without chipping.
• Use cutting tools with protective coatings, such as diamond or carbide, to increase their strength and durability.
• Use tools with multiple cutting edges, which can evenly spread the cutting forces and reduce the risk of chipping.

Different Types of Cutting

• Hitting Cutters

One of the primary concerns in machining is the occurrence of hitting cutters. It happens when the cutting tool removes a significant amount of substance from the workpiece and strikes with it during the procedure, causing high levels of vibration & harm to the workpiece. Various factors can participate to hitting cutters, such as using a cutting tool with a large diameter, utilizing improper machining techniques, or setting an incorrect safety height. To prevent hitting cutters, it is essential to choose a cutting tool with a smaller diameter, choose a suitable machining technique depending on the tool and work requirements, and set a higher safety height to prevent hitting the clamping.

• Bouncing Cutters

Another problem in machining is bouncing cutters, which can lead to tool deformation and material damage caused by excessive vibration resulting from too much force on the equipment. Factors that participate in reflecting cutters include the diameter and length of the tool and the amount of power exerted on the device during cutting. To mitigate the risk of tool deformation, selecting a larger diameter tool and a shorter tool length can be beneficial. In addition, reducing the amount of force applied to the device while cutting can also assist in minimizing tool deformation.

• Overcutting

The third problem in machining is overcutting, which occurs when excess material is cut beyond what is required, destroying the workpiece. To prevent overcutting, it is crucial to monitor the machining path and exercise caution while cutting carefully.

Tips to Avoid CNC Machining-defects

To prevent defects in CNC Machining production processes resulting from common mistakes, Below are some fundamental tips:

• Know your material

Before starting a CNC machining operation, it is important to ensure that the correct settings and lathe are being used for the specific type of metal being worked on. It is essential to consider the physical and mechanical properties of the workpiece material when selecting the appropriate tool material and geometry. Additionally, it is crucial to apply the Optimal machining speed and feed rate based on the material type.

When working with extremely hard metals, such as cast iron, it is possible that your lathe may not be capable of performing the necessary operations. Therefore, it is essential to consider the equipment model and specifications before starting the programming process.

While the care & dedication of your teammates are crucial, it is also important to have a reliable partner to assist with predictive, preventive, and corrective maintenance cases.

• Cross-check the digital instructions

One of the most common errors in CNC machining production is a syntax error or simple spelling when entering the code. Although modern lathes typically have mechanisms in place to prevent breakdowns, even a small mistake like this can bring the entire production chain to a halt and potentially cause damage to your equipment. Therefore, it is crucial to perform a thorough cross-check of the G-code to avoid such errors.

• Preventive maintenance

A team of qualified Specialists for repairing and maintaining your CNC machine is essential. It is important to keep up with periodic and scheduled maintenance, which includes services that enhance tool performance, such as:

• Applying lubricant to the components in motion
• Inspecting and refilling fluids
• Extraction and replacement of filters.

Finding the Best CNC Machining Provider

If you are considering outsourcing your Organization’s CNC machining production capabilities, it is crucial to partner with a reputable provider that has been in business for a substantial period, offers all the necessary support under one roof, and caters to a diverse range of industries. Creatingway is a leading provider of CNC machining services. With the country’s top engineers & designers all in-house, Creatingway ensures that every aspect of the process, from design to cutting technique, is appropriate for the project.

Creatingway concentrates on CNC manufacturing, prototype machining, low-volume manufacturing, metal fabrication, and parts finishing services, providing you with the best support. ask us one inquiry now.

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