Collets and their accessories are some of the smallest components in your tooling setup, but they have a big impact on runout, tool life and surface finish.
With the right collets and accessories, you turn spindle power into stable, predictable cutting performance. With the wrong ones, you get vibration, broken tools and inconsistent quality.
Modern collet systems are available in fine diameter increments with high clamping force and tight runout control, making them a key element in any high-precision CNC tool holding strategy.
What is a collet, and why does it matter?
A collet is a slotted sleeve that grips the tool shank when tightened inside a collet chuck or nut. It sits between the tool holder and the cutting tool and is responsible for:
• Centering the tool on the spindle axis
• Clamping the tool securely under load
• Transmitting torque without slippage
• Often guiding coolant to or around the cutting edge
Premium collets are offered in 0.1 mm diameter steps to closely match tool shanks, which improves runout and clamping force.
For The Hands-On Operator, that means fewer surprises at the machine. For The Operational Optimizer, it means more consistent quality and tool life.
Main types of CNC collets.
ER and tapered collets
ER (and similar tapered) collets are widely used on machining centres and turning machines for:
• Drilling and reaming
• End milling
• General-purpose tool holding
High-quality ER collets are:
• Available in fine diameter increments for “just-fit” clamping
• Runout-inspected at multiple positions and lengths to ensure accuracy in the cut
They form a flexible backbone for mixed production where tool diameters and operations change frequently.
Straight collets
Straight collets are used for clamping smaller cylindrical tool shanks, often in high-precision or high-speed applications. They can be configured to:
• Supply coolant through the tool
• Supply coolant around the tool periphery
This makes them well suited for drilling, micro machining and finishing operations in demanding materials.
Micro collets for micromachining
When you work with micro drills and small end mills, concentricity and balance become critical. Micro collets are designed for exactly that:
• Available in 0.1 mm steps to match very small shanks
• High clamping force despite compact size
• Runout accuracy at the nose in the low micron range when used with matching chucks
For medical, electronics and precision mould work, these collets help keep small tools stable at high spindle speeds.
Coolant-focused collets.
Coolant delivery is crucial for tool life and chip control. Modern collet families therefore include:
• Coolant-through collets that seal around the shank and feed coolant directly to the tool tip
• Peripheral coolant collets (jet collets) that direct coolant to the cutting edge from the outside, minimising loss from centrifugal forces at high speed
These designs improve chip evacuation and cooling, especially in high-speed end milling and deep-hole drilling
Accessories that make collets perform.
Collets are only one part of the system. Collet accessories are just as important for safety, performance and ease of use.
Collet nuts
High-performance collet nuts are engineered to:
• Use slot-free outer diameters for better rigidity and balance
• Integrate thrust ball bearings to reduce friction and improve clamping force
• Offer sealed variants to maintain a reliable coolant seal at higher pressures
The right nut reduces vibration, protects the collet and helps maintain runout over time.
Wrenches and assembly tools
To tighten and loosen collets correctly, you need the right tools:
• Collet wrenches with one-way clutch and ratchet function for secure, easy tightening without slipping
• Collet ejectors that quickly insert and remove small collets from nuts, reducing risk of damage
• Assembly stations that provide a stable, safe place to assemble tool holders and collets
This reduces the risk of over- or under-tightening and makes daily handling safer for operators.
Cleaning, storage and maintenance accessories
Clean, well-maintained collets and holders are essential for long-term accuracy. Supporting accessories include:
• Cleaning tools for collets, nuts and spindle tapers
• Storage cases that protect collets and small accessories from dirt and damage
• T-slot cleaning tools that help keep machine tables free from chips and contamination around fixtures
For The Operational Optimizer, these details matter, they support standardisation, reduce variability and extend tool holder life
What collets & accessories mean for each role.
For the Hands-On Operator
• More stable cutting with less chatter and tool slippage
• Easier tool changes with the right wrenches and ejectors
• Fewer problems caused by dirt, damaged collets or poor coolant delivery
For the Operational Optimizer
• Improved runout and balance for higher cutting data
• Longer tool life and fewer unexpected failures
• A more robust, standardised tool holding setup across machines and shifts
For the Strategic Owner
• Better utilisation of existing machines and tooling
• Lower cost per part through longer tool life and reduced scrap
• A tooling foundation that supports automation and unmanned machining
Collets & accessories from Duroc Machine Tool
Duroc Machine Tool operates in seven markets – Sweden, Norway, Denmark, Finland, Estonia, Latvia and Lithuania – supplying machining solutions, tools, service and support to manufacturing companies.
Within collets and accessories, we help you with:
• ER, straight and micro collets for drilling, milling and micromachining
• Coolant-through and peripheral-coolant collet solutions for demanding applications
• Matching nuts, wrenches, ejectors and maintenance accessories
• Application support that ties collets, tool holders, cutting tools and machine parameters into one coherent solution
Our goal is simple: to help your people and machines deliver stable, predictable performance.
Ready to review your collet setup?
If you see inconsistent runout, tool slippage, coolant problems or vibration, your collets and accessories may be part of the cause.
