Workholding

For turning centers, three-jaw chucks are the most common workholding device, gripping the outside of a bar or other type of material as the main spindle spins and turning operations are performed. For long parts, a tailstock with a dead center (doesn’t rotate) or live center (rotates with the workpiece) are used to support the opposite end of the workpiece during turning. Expanding mandrels are also available to expand inside a tube or machined bore to grip the part during turning. These provide the cutting tool full access to the entire outside diameter of a part. Quick-change collets are becoming more common to speed changeovers to new barstock sizes. A range of workholding options are available for milling machines, including vises, magnets, vacuum tables and hydraulic-actuated clamps.

Precision Machining Technology Review: October 2024
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Precision Machining Technology Review: October 2024

Production Machining’s October 2024 technology showcase includes some of the latest technology from Ceratizit, Kennametal, Mate Precision Techologies, Horn and Mazak.

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ESSENTIAL READING

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Workholding

Bar Feeder Basics

Some primary factors are often overlooked when considering how to justify the implementation of a bar feeder for turning operations.

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Workholding

Understanding CNC Collet Chucks

Workholding for turning is usually fairly basic: The selection comes down to chucks or collets. This article looks at when to consider the collet chuck and what kind might be best for a given application.

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Workholding

Discovering the Benefits of Collet Chucks

For shops making all types of parts, collet chucks can provide faster change-over, an increased gripping range, high rigidity and reduced maintenance.

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Precision Workholding Delivers Accuracy and Production Capabilities

Holding the workpiece precisely is becoming an integral aspect of the machining process. It's more than presenting the blank to the cutter; it also includes repeatability from blank to blank.

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Subspindle Workholding Options

The advent of subspindle turning operations has impacted throughput for many shops. Understanding workholding options available for backworking can help a shop make better decisions when specifying how to hold parts for op. 20.

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Workholding

Precision Workholding Offers Multiple Advantages

As American manufacturing continues to transition from the mass production of conventional parts to the manufacture of complex, high-value components in relatively small lot sizes, precision workholding has assumed increased importance

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Latest Products

Workholding

Dillon Reversible Hard Jaws Provide Secure Parts Gripping

The company’s reversible hard jaws are designed to decrease the time and cost of tool setups.

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Workholding

SMW Mechatronic Grippers Automate Key Processes

The Motiact mechatronic gripper series is designed to perform precise, consistent, accurately monitored gripping operations in automated work cells.

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Workholding

Destaco Electric Power Clamps Enable Flexible Production

The 92W series electric power clamps feature integrated intelligence to reduce the need for additional components.

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Workholding

SMW Autoblok Vise System Provides Omnidirectional Clamping

The Plus5 V5 Zero Point Vise system interfaces with all industry-standard products using 52 mm or 96 mm pin spacing, enabling it to readily become part of existing workholding systems.

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Workholding

Fairlane Workholding Components Enable Modular Positioning

Fairlane Products Inc.’s Swivots workholding components swivel, pivot and tilt to compensate for angles and irregularities of the workpiece.

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Workholding

Dillon Soft Top Jaws Improve Concentricity, Chuck Balance

The soft jaws are designed to provide better concentric performance chuck balance, as well as enable a longer jaw life because of the increased jaw accuracy.

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Featured Posts

Workholding

When to Use a Diaphragm Chuck

The accuracy and repeatability of these chucks make them well suited for a number of workholding applications, including turning and grinding.

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The Value of Auto Adjust Magazine Bar Feeders

This bar feeder is designed to offer the flexibility to enable CNC turning centers to perform short-run work that would otherwise require frequent setups over a range of barstock diameters.

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Job Shop Discovers and Fills a Fishing Need

The promise of a product line for improved mounting of electronic fish finders led this Missouri job shop to an automated turning process.

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Workholding

Bar Feeder Designed with Swiss-Types in Mind

New technology enables this bar feeder to fully support the bar pusher and stock from inside the unit all the way to the spindle of a sliding headstock lathe.

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Workholding

Video Tech Brief: Bar Feeder Technology Optimized for Swiss-Types

This bar feeder design is said to offer high guidance quality with minimum vibration and noise development for sliding-headstock machines.

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Workholding

Workholding Facilitates Fast Changeovers for Robotic Surface Finishing Systems Manufacturer

This manufacturer finds value in modular workholding technology to speed production of toolholders and other components used in its automated surface finishing systems.

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World Machine Tool Survey
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FAQ: Workholding

How does a three-jaw chuck work?

For turning centers, three-jaw chucks are the most common workholding device, gripping the outside of a bar or other type of material as the main spindle spins and turning operations are performed.

What is a mandrel?

Expanding mandrels are available to expand inside a tube or machined bore to grip the part during turning. These provide the cutting tool full access to the entire outside diameter of a part.

Source: Expanding The Expanding Mandrel's Usefulness

What is a collet?

Collets are generally used when the diameter of the part or bar to be gripped ranges from 1/16 inch to 2.5 inches. Compared with standard triple-jaw chucks with soft jaws, standard collets tend to be inexpensive and more accurate for gripping in the small-to-medium range.

When a collet-type workholding device is used, the part being gripped and machined will be closer to the headstock bearings on the machine tool or indexing fixture than is the case when using a power chuck.

Source: Collets Vs. Chucks

How do you use a vise?

According to Mr. Wolfe, "any vise has a bending moment associated with the clamping force applied. Take for example a 6-inch vise held down by its four corners. When the vise jaws close to clamp on a workpiece, the unsupported middle will tend to bend up from the machine table. It can move 0.002 inch or more. On precise parts that may be all the tolerance there is. My suggestion is always to secure the vise base as close as possible to the center distance between the movable and fixed jaws."

Another problem for many shops is consistency from operator to operator. "Rarely do two operators use the same clamping force on a vise," says Mr. Wolfe. "Deflections of the workpiece blank can cause inaccuracies. A more expensive but more accurate pull-type vise will help reduce some clamping variability. A simple torque handle will help achieve consistent clamping on both the pull-type and the more common push-type vises."

Make it a rule of thumb," says Mr. Wolfe, "to always try to keep the workpiece as close to the vise base as possible. Usually parallels work better on this type of setup than step jaws because the operator can check the seat of the part by trying to move the parallel. If it's snug, it's good."

Source: Flexibility Is A Vise

Marubeni Citizen CNC
Star Swiss-type automatic lathes