How to Use Shrink to Fit Tool Holders

Shrink Fit Tool Holders are widely used in modern CNC machining due to their high precision, excellent balance, and strong clamping force. Compared with mechanical holders, shrink fit holders rely on thermal expansion to grip cutting tools securely, making them ideal for high-speed and high-accuracy applications. This article explains how to use shrink to fit tool holders correctly, while also introducing the benefits of shrink fit tool holders, compatible machines, and common BT and CAT standards.

What Are Shrink Fit Tool Holders?

A heat shrink tool holder is a type of CNC tool holder that uses controlled heating to expand the holder bore. Once expanded, the cutting tool is inserted. As the holder cools, it shrinks back to its original size, tightly clamping the tool with uniform 360-degree contact.

Common types include:

• BT Shrink Fit Tool Holders

• BT40 Shrink Fit Holders

• BT30 shrink fit holders

• CAT 40 shrink fit tool holders

• Command shrink fit tool holders

These holders are widely used in CNC machining centers, mold making, aerospace, and automotive manufacturing.

Equipment Needed Before Installation

To use shrink fit tool holders, the following equipment is required:

• Shrink fit tool holder machine

• Heat shrink machine for tool holders (induction or hot air type)

• Protective gloves and safety glasses

• Clean cutting tools with the correct shank diameter

A dedicated shrink fit tool holder machine ensures uniform heating without damaging the holder material.

Step-by-Step Guide: How to Use Shrink Fit Tool Holders

Step 1: Prepare the Tool Holder and Cutting Tool

Ensure the shrink fit holder bore and cutting tool shank are clean, dry, and free of debris. Any contamination may affect clamping accuracy.

This step applies to all models, including BT Shrink Fit Tool Holders, BT40 Shrink Fit Holders, and CAT 40 shrink fit tool holders.

Step 2: Heat the Shrink Fit Tool Holder

Place the heat shrink tool holder into the heat shrink machine for tool holders. Activate the heating cycle to expand the bore slightly.
Do not overheat, as excessive heat may reduce tool holder lifespan.

Step 3: Insert the Cutting Tool

Once heated, quickly insert the cutting tool into the expanded bore to the required depth. This process is the same for BT30 shrink fit holders, BT40 Shrink Fit Holders, and other sizes.

Step 4: Cool Down the Holder

Allow the shrink fit tool holder to cool naturally or use a cooling station if available. As it cools, the holder contracts and grips the tool securely.

Step 5: Check Runout and Balance

After cooling, inspect the assembly for proper seating and measure runout. High-quality shrink fit tool holders typically achieve extremely low runout, improving surface finish and tool life.

Benefits of Shrink Fit Tool Holders

Understanding the benefits of shrink fit tool holders helps explain why they are widely used in precision machining:

• Ultra-low runout for high-accuracy machining

• Uniform clamping force without Collets or screws

• Excellent balance for high-speed spindles

• Improved tool life and surface finish

• Slim nose design for better reach and accessibility

These advantages make shrink fit holders superior for finishing, drilling, and high-speed milling.

Common Applications

Shrink fit tool holders are commonly used in:

• CNC machining centers

• Mold and die manufacturing

• Aerospace component machining

• Automotive precision parts

• High-speed milling and finishing

Both Command shrink fit tool holders and BT Shrink Fit Tool Holders are popular choices in these industries.

BT vs CAT Shrink Fit Tool Holders

When selecting a holder, it’s important to match the taper standard:

• BT Shrink Fit Tool Holders / BT40 Shrink Fit Holders
  Widely used in Asian and European CNC machines.

• CAT 40 shrink fit tool holders
  Commonly used in North American CNC machining centers.

Both types offer the same performance benefits when used with a proper shrink fit tool holder machine.

Maintenance Tips

• Avoid overheating the holder repeatedly

• Keep bores clean to maintain accuracy

• Use the correct heat shrink machine for tool holders

• Inspect holders regularly for wear or discoloration

Proper maintenance extends the life of shrink fit tool holders and ensures consistent machining accuracy.

Learning how to use shrink to fit tool holders correctly is essential for achieving maximum precision and tool life in CNC machining. With the right shrink fit tool holder machine, proper heating, and careful handling, shrink fit holders—including BT40 Shrink Fit Holders, BT30 shrink fit holders, CAT 40 shrink fit tool holders, and Command shrink fit tool holders—deliver outstanding performance in high-speed, high-accuracy applications.