10 Key Steps in Milling Tool Fabrication for Modern CNC Machining

10 Essential Stages in Producing Milling Tools for Advanced CNC Machining

Milling tool fabrication is a process that is rapidly evolving. With the continual evolution of manufacturing technologies, milling tool fabrication is now more specialized than ever before. It has a direct impact on machining accuracy, tool life and overall productivity.

Therefore, whether you are manufacturing parts for the aerospace industry or you are producing a simple industrial part that can be used daily in most companies; your CNC milling tool quality will have a critical impact on achieving quality and consistent results.

Today’s manufacturers depend heavily on the latest advancements of the milling tool solutions to achieve tighter tolerances, less downtime, and greater overall efficiency than ever before.

In this guidebook, we will walk through each of the 10 key steps of milling tool fabrication as a way of demonstrating how the milling tools define what will be accomplished using CNC Milling.

1. Understanding Application Requirements

In order to create an effective milling tool, a manufacturing engineer must first understand what the tool will be used for. Engineers need to know things such as spindle speed, material hardness (HRC), axial forces and thermal conditions. This is very important because milling tools for aluminium are very different to those used on hardened steels and titaniums. An analysis of the entire process environment allows tool makers to create CNC Milling tools that will provide the best possible results.

2. Choosing the Right Tool Material

The performance of milling tools greatly depends on the substrate chosen for that tool. Each substrate has different characteristics.

• HSS: Cost effective, Versatile for general use

• Carbide: Great hardness - Great heat resistance.

• Ceramic: Excellent strength under high-temperature conditions.

• PCD: Best Substrate for non-ferrous material applications

When choosing a substrate for a milling tool during the fabrication process, it is important to choose the proper substrate so that the tool will perform optimally in terms of wear resistance, accuracy, and longevity. Carbides are the most used substrates for modern CNC machines because they strike a balance between toughness and hardness.

3. Powder Processing and Sintering (for Carbide Tools)

The production of carbide tools includes adding small pieces of tungsten carbide (TC) together with a binder material (bond) such as cobalt. The mixture becomes a powder and can then be pressed into a mold and heat treated via the process of sintering. It is during this process that the TC is fused together creating a material that is very dense and extremely hard - ideal for CNC milling operations. Therefore, any error in the accuracy of this process will have a direct effect on the final physical strength of the carbide tool.

4. Precision Shaping and Forming

After preparing the tool blank, the actual forming starts using CNC grinding machines, laser machining systems, and other advanced EDM manufacturing processes to create the basic geometric shape of the Tool blank, along with the flute profiles, rake angles, helix angles and dimensions. It is very important that the tool blank is formed with absolute precision since any slight deviation from specification could result in poor chip evacuation, heat dissipation or surface quality.

The multi axis grinding (MAG) systems used in manufacturing advanced milling tool solutions provide sub-micron accuracy with high levels of repeatability during the mass production phase of manufacturing.

5. Edge Preparation and Honing

Sharp edges are useful when cutting for seconds or minutes, but under high-stressed cutting conditions, the life of a tool can be increased considerably with a micro-honed edge. Edge prep involves rounding or smoothing the cutting edges to decrease the number of micro-fractures in addition to making the edges stable. Common methods of performing this step are brushing, drag finishing and micro-abrasive blasting. This step is most important for tooling used in high-speed CNC milling due to increased forces and temperatures associated with these applications.

6. Coating Application

Today's CNC manufacturers use coated tools extensively. Coating applications help protect tools against wear, increase their heat resistance and decrease their friction. Some of the most common coatings applied are:

• TiN (Titanium Nitride)

• TiAlN (Titanium Aluminium Nitride)

• AlTiN (Aluminium Titanium Nitride)

• DLC (Diamond-Like Carbon)

The right coating can extend the life of tools for high-demand applications by as much as 200–500% and is a critical factor to consider in select applications.

7. Quality Inspection and Testing

Every tool is thoroughly examined for quality assurance at the level of industry standards and for this process all Laser Measuring Devices, high resolution microscopes, and coordinate measuring machines will measure the following parameters on tool inspection until passed all quality assurance tests.

• Dimensional Tolerances

• Runouts

• Surface Finish

• Coating Thickness

• Balance of Tool

As CNC-based manufacturing increases in complexity, so too does the requirement for quality assurance as a major factor for the successful implementation of milling tool solutions. Oftentimes manufacturers will conduct performance testing of sample tools to determine the cutting performance and longevity their tools are capable of delivering.

8. Balancing and Polishing

High-speed CNC milling requires proper tool balance. If a tool is not balanced, it can cause vibration, excessive tool wear, poor finish quality, and spindle failure. By polishing the flute (cutting edge) of the tool, you will create an even flow of chips during cutting operations, which creates less heat during cutting and improves the overall efficiency of the tools used in these applications, especially in industries that utilize high-precision machining (such as aerospace, die/mold machining, automotive component production, etc.)

9. Customization and Special Geometry Development

Some applications require unique or custom milling tools because of special materials and geometries. Customizing can mean designing tools with variable helix designs, multiple flutes, or corner radius variations, and even through cooling systems. This process gives manufacturers the ability to develop tools specifically for a given application that will allow for improved cycle times and improved accuracy.

10. Packaging and Traceability

After the tool has been manufactured, the last step is to properly package and label the tool. Each tool has a batch number, material specification, coating type, and customer order number. With the ability to trace the tool for its entire lifetime, it is crucial in defense and medical device industries where the quality is very important.

Final Thoughts

Due to the complex nature of designing modern CNC mills, manufacturers face great challenges when producing high quality products. As technology continues to evolve, providing powerful, efficient and precise CNC milling tool solutions will remain an ongoing challenge for many manufacturers. We offer state-of-the-art CNC mills designed specifically for contemporary production processes that are capable of meeting today's demanding machining applications.

Contact us today to find out how we can help with your tooling needs or to receive a price quote on performance milling tools tailored specifically for your business!