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Types and Features of Chucks and Soft Jaws, Related Fixtures

Scroll Chucks
Soft Jaws
Soft Jaw Molding Holder (Chuck Mate)
Soft Jaw Molding Holder (Jaw Lock)

Scroll Chucks

Scroll chucks are hand-tightened chucks used to clamp the workpiece in a lathe.
There are two types of chuck jaws: split jaw types and integrated jaw types.
There are also four-jaw chucks in addition to three-jaw chucks.
*The diagram below shows a chuck with an integrated jaw.

Features

As all of the jaws move the same amount at the same time, it makes it easy to remove the center of the work material (workpiece).

Useful Info: Lathe Processing and Soft Jaws

Structure of a Scroll Chuck with Split Jaws

Advantages of Split Jaw Types
(1) Easy to handle as only the upper jaw can be replaced
(2) Can be used with soft jaws for various molding work depending on the workpiece

Inner Jaws and Outer Jaws

Inner jaw
Used to clamp the outer diameter of shaft material and the inner diameter of pipes, etc.

Outer jaw
Used to clamp the outer diameter of flanges.

Split Jaws and Integrated Jaws

Split jaw
The lower and upper jaws can be attached and detached using bolts.

Integrated jaw
The inner and outer jaws are used alternately depending on the work.

Main points!

The type and size of the chuck differs depending on the size and shape of the work material (workpiece) to be clamped. Select the clamping range (mm) required after checking the work material (workpiece) to be clamped.
Check the type of jaw. Choose from either split jaw or integrated jaw types.
Chuck size (chuck outer diameter) Clamping range

Soft Jaws

Soft jaws are attached to the chuck on a machine tool and used to hold machine components and other workpieces.

Features

It is generally made of S45C steel.
Unlike the hard jaws of readymade tools, the shape of soft jaws can be cut using tool bits depending on the shape of the work material (workpiece).

Soft jaws are also used as replacement jaws for the scroll chucks and hydraulic/pneumatic chucks used in general purpose lathes, CNC lathes, and machining centers.

Names of Chuck Parts

Soft jaws used in power chucks (hydraulic/pneumatic type) are fixed in place using a jaw nut and jaw mounting bolts. When changing setup, as it takes too much time to replace jaws when sharing jaw nuts, jaw nuts should be attached to the replacement jaw in advance. In doing so, jaws can be replaced easily.

Main points!

Check the name of the chuck manufacturer.
Check the model of the chuck.
Check the type of soft jaw. (Standard jaw, small-diameter jaw, wide jaw, large jaw)

Soft Jaw Molding Holder (Chuck Mate)

Soft jaw molding holders are a type of fixture used to enhance soft jaw precision in line with the shape of the work material (workpiece)

Features

As the pin holes on the outside of the jaw are used as points of support, center runout is improved and clamping strength increases.
Previously, through molding and inner diameter chuck molding required that rings be made in line with the relevant size. However, as these holders have a slotted hole shape which pins can slide through, these rings are no longer needed.

Differences Between Conventional Jaw Molding Holders and Soft Jaw Molding Holders

Figs. 1–3 show conventional molding methods In Fig. 1, which is the most common method, the difference in strength of the soft jaw when holding a core metal and when holding a work material (workpiece) causes a gap to open at the front of the soft jaw, causing runout and decreased clamping strength. Fig. 4
When using a soft jaw molding holder, in addition to the molding methods shown in Figs. 1–3, molding can be undertaken in the same way as when holding a work material (workpiece), eliminating runout and maximizing clamping strength. Fig. 5

Main points!

Check the type of chuck used.
Check the size (inches) of the chuck used.
Select the size of the fixing pin (mm).
- *The diameter of the counterbore hole (fixing pin nominal diameter) of the chuck soft jaw.

Soft Jaw Molding Holder (Jaw Lock)

Soft jaw molding holders are a type of fixture used to enhance soft jaw precision in line with the shape of the work material (workpiece)

Features

Minimizes soft jaw deterioration through stepless fine adjustments.
Extremely convenient for soft jaw molding in compact clamping.
Demonstrates efficiency in soft jaw through processing.
Processing range expands by reversing the direction of jaw attachment.

Use

As a soft jaw molding fixture for three-jaw chucks.
Can be used in hydraulic chucks, power chucks, pneumatic chucks, scroll chucks, fixture chucks, and milling machine chucks.

It is composed of three parts—the main body, adjustment ring, and jaws—and the position of the jaws (pins) can be adjusted by turning the ring.
The range of adjustment can be increased by switching the direction of the jaws.