A SEEMINGLY SMALL ELEMENT THAT HOLDS THE POWER TO MAKE OR BREAK YOUR CNC OPERATION

Have you ever calculated the true cost every time a CNC cutter breaks?

It's far more expensive than just the expense of replacing a broken tool. Consider the hidden costs: the machine downtime while changing out the tool and its collet, the cost of a ruined workpiece, and the lost productivity as your team scrambles to adjust the workflow. It all adds up quickly, and these losses can easily run into thousands of dollars per incident.

But did you know that over 80% of these breakages can be traced back to one critical factor that is surprisingly easy to address? Yes, you guessed it – CNC toolholding. Let's find out how the toolholding setup can make or break your operation…

Toolholding is often an overlooked aspect of CNC operations, yet it plays a pivotal role in machining profitability. It is not just an accessory option, it’s a critical component to your ongoing success and cost savings. The condition, maintenance, and precision of your toolholding setup directly impact tool life, machining accuracy, and the quality of your finished products.

Most CNC production tools are now made from tungsten carbide, allowing them to last longer and be fed faster due to their increased hardness and rigidity. However, these properties make them completely unforgiving of any vibration. Toolholding is the unsung hero of CNC machining, ensuring tools are firmly secured and run with minimal runout and vibration.

Key Components of CNC Toolholding

Collets:

A collet is the element that holds tools in place on CNC machine during operations. The collet grips the cutting tool with a high degree of precision, ensuring minimal runout and vibration, both of which are critical for maintaining tool life and achieving the high-quality surface finish you’re looking for.

Using a worn collet leads to increased runout and allows the cutting tool to move in the cut, increasing noise and vibration and resulting in poor surface finish; potentially damaging the tool, the workpiece and the expensive spindle nose bearings on the machine.

Regular inspection and replacement of collets is critical to preventing such issues. Collets should be replaced every 400-600 working hours due to their exposure to heating and cooling cycles that degrade their tempering and concentricity.

Common indicators for replacement include:

• Decreased Clamping Force: If tools or workpieces start slipping, it's a definite sign the collet replacement is well overdue and it urgently needs to be replaced.
• Visible Wear or Damage to the cutting tool or collet: Cracks, chips, or deformations are clear signs that a collet should be replaced.
• Loss of Precision: If you suspect or notice a decline in machining accuracy, the first step (an inexpensive one, too), is to replace the collet.
• Tool breakage in or near the collet

To get the best out of your cutters, you need to use good, clean collets - watch our instructional video on how to look after your collets:

Collet Nuts:

Collet nuts, though small in size, have a significant impact on CNC machining operations. These components exert uniform pressure around the tool shank. They are designed to provide a tight, concentric grip, minimising runout and vibration during machining operations. 

Over time, collet nuts can wear out due to the continuous tightening and loosening cycles, exposure to cutting fluids, and general usage. Regular inspection for signs of wear, such as rounded or damaged threads, is crucial. 

The quality of the collet nut directly affects the gripping force of the collet and, subsequently, the performance of the cutting tool.

Here are the most common mistakes to avoid:

• Cross-Threading: One of the most common mistakes when handling collet nuts is cross-threading. This happens when the nut is not aligned properly with the threads of the toolholder, causing damage to both components. Always ensure that the collet nut is threaded on smoothly and without resistance.
• Incorrect Collet Seating: Another frequent error is not seating the collet correctly within the collet nut before threading it onto the toolholder. The collet should be clicked into place within the collet nut before any threading occurs to prevent damage and ensure proper tool grip. 

Factory Preset Torque Wrench:

A factory preset torque wrench is the perfect tool used for repeatedly accurately tightening collet nuts to the correct manufacturer’s specified torque, ensuring a secure grip on the cutting tool without over-tightening or under tightening.

The primary function of a torque spanner in CNC toolholding is to ensure collet nuts are tightened to the exact torque specified by the toolholder and collet manufacturers. This precision is essential for several reasons - watch our video to find out more:

ISO and HSK Toolholders:

ISO and HSK toolholders are known for their high precision and excellent rigidity, making them ideal for high-speed and high-precision machining applications. If there are ongoing problems with noise or finish and you have replaced collets and collet nut without improvement, then you need to replace the toolholder.

Toolholders are under considerable tension and pressure when cutting and temperature fluctuations can be up to 60°C. Over time, this can cause them to warp and/or lose their tension, causing the cutting tool to lose its accuracy and concentricity. Finish becomes inferior, noise and machine vibration increases.

The two main areas of wear are:

• The tapers: When the taper on the toolholder wears, they cease to mate perfectly with the interface taper in the spindle of the CNC. Their grip is no longer concentric and power transmission is compromised.
• The collet nut: When collet nuts become distorted and the threads worn, the collet ceases to be evenly and concentrically held in the toolholder.

CNC toolholder clip or fork:

Toolholder clips/forks are designed to securely store and manage toolholders when they are not in use. These components might seem minor in the grand scheme of CNC operations, but their importance cannot be overstated. Proper storage of toolholders ensures they remain clean, undamaged, and ready for immediate use, thereby minimising downtime and maintaining machining accuracy. 

Contamination of toolholders can lead to precision issues and increased wear on both the toolholder and machine spindle. Toolholder clips and forks help keep toolholders in a controlled environment, reducing the risk of contamination from oil, dust, or other debris that can accumulate on exposed surfaces.

Our CNC Toolholder Clips are available for both ISO and HSK toolholders and built with anti-crack reinforced material to resist temperature changes and precision clutch tolerance. Designed to handle a loading capacity of 8-10kgs and a dynamic balance grade of G2.5 30000rpm.

Toolholding Changing Device:

A toolholding changing device, also known as a tool changer or tool clamping device, is a specialised piece of equipment designed to facilitate the quick and accurate changing of toolholders in CNC machines. Featuring perfect precision and reliability, it delivers perfect gripping and centring of tools for super accurate and fast setup. 

During a production run that requires frequent tool changes, a toolholding changing device allows operators to quickly and safely switch out tools, maintaining productivity, reducing the risk of errors that could occur with manual changes and minimising downtime during tool changes.

Loading Tools Correctly and Ensuring Proper Tightening

Loading tools into toolholders correctly is a fundamental practice that significantly impacts machining performance and tool life. When inserting a tool into a collet, it’s crucial to follow the correct procedure:

Steps to Load Tools:

1. Insert the collet into the collet nut before loading it into the toolholder. This ensures the collet is seated correctly and prevents damage to the toolholder's taper.
2. Thread the collet nut onto the toolholder without cross-threading. Once it's mostly on, insert the cutting tool to the correct depth—typically, 80% of the collet needs to be filled for optimal grip.
3. Use a torque spanner to tighten the collet nut to the specified torque setting. This ensures the tool is held securely without over-tightening.

Consequences of Incorrect Tightening:

• Under-tightening: If the collet nut is not tightened enough, the cutting tool may slip during machining. This not only affects the quality of the finish but also poses a risk of tool breakage or coming out of the holder at 20,000 rpm and damage to the workpiece.
• Over-tightening: Over-tightening puts excessive stress on the cutting tool and the toolholder, reducing tool life and affecting machining accuracy. It distorts the collet, compromising its gripping ability and leading to tool runout.

Best Practices for Toolholding Maintenance

Regular inspection and maintenance of toolholding components are vital for ensuring optimal performance and longevity.

Here’s what we recommend you should do:

• Regular Inspection: Check for signs of wear, such as cracks, deformation, or excessive wear on collets, toolholders, and collet nuts. Replace any components that show signs of damage immediately.
• Cleaning: Clean all toolholding components regularly to remove debris and contaminants. Use top quality cleaning products and a dedicated brush to clean collets, tapers and toolholders.
• Proper Storage: Store toolholders in a clean, dry environment to prevent corrosion. Use dedicated storage racks or containers to avoid damage and contamination.
• Calibration: Periodically calibrate your CNC machine and toolholding components to maintain precision. This is especially important for high-precision applications where even minor inaccuracies can lead to significant defects.

As a rule, it's generally more cost-effective and worthwhile to do simple cleaning and maintenance at the end of each shift. 

Why is the proper maintenance essential for profitability?

Production stops if the CNC machine breaks down, and downtime is costly! To ensure your CNC router is operating at its best, we recommend you take the time to clean it regularly. This can include wiping down the machine, vacuuming out any dust and debris, and lubricating the moving parts. A clean CNC router not only ensures better performance and accuracy but also improves productivity and extends the life of the machine, saving you money in the long run.

What should you look at daily, weekly, monthly, every 1000 working hours and annually? Download our suggested maintenance checklist here to avoid potential failures and unplanned downtime. 

The Critical Importance of Precision in CNC Routing

In CNC routing, the precision of your toolholding setup is not just a factor; it’s a game-changer. Poorly maintained or incorrect toolholding components can drastically reduce tool life, degrade finish quality, and increase downtime due to frequent tool changes and adjustments.

• Impact on Tool Life: A properly maintained toolholding system minimizes runout and vibration, which in turn extends the life of the cutting tools. Tools that run smoothly and accurately last longer, providing better value and reducing overall costs.
• Impact on Finish Quality: Precision in toolholding ensures that cutting tools remain stable and concentric during operation, which is critical for achieving a high-quality surface finish. Poor toolholding can lead to chatter marks and uneven cuts, compromising the quality of your final product.
• Impact on Downtime: By prioritising the maintenance and proper use of CNC toolholding components, you can reduce downtime significantly. Efficient tool changes and reliable toolholding mean that your CNC machines spend more time cutting and less time being adjusted or repaired.
• Impact on Machine Spindle Bearing Life: Please be aware that every time you turn your spindles on, they’re rotating at 18,000 RPM plus! Toolholding accuracy has a direct impact on the life of those extremely expensive spindle nose bearings. If you can delay a $10,000+ bill – plus the cost of a couple of weeks of downtime, isn’t it just common sense to take a few easy steps as outlined above and reap the benefits?

You ask, we answer!

Don’t let small oversights in toolholding lead to big problems in your machining process. Understanding the critical role of CNC toolholding and implementing best practices for maintenance and usage are essential for maximising efficiency, improving product quality, and ensuring the longevity of your cutting tools and machines.

By investing in high-quality toolholding equipment and proper maintenance, you’re not just saving money; you’re protecting your investments, your workforce, and your reputation. Embrace precision, prioritise maintenance, and watch as your CNC operations thrive with reduced costs, enhanced productivity, and superior product quality.

At Tungsten & Tool, we have the expertise and resources to help you choose the best tools for your job specific needs, whether you're manufacturing windows and doors, stairs, furniture, signs, shop fit-outs, cabinets, bathrooms or kitchens.

Feel free to contact us at 0800 488 647 or sales@tungstenandtool.co.nz for more information.