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Home |  Technical Information |  Shafts

Technical information

ASK provides all the technical details you need to know about our products.

In this section we provide requirements for use, structural information and other technical details about ASK products. Please contact us if you have any inquiries.

Shafts

1.EXCLUSIVE SHAFTS FOR BALL BUSHES 2.ACCURACY
3.DOCUMENT FOR DESIGN  

EXCLUSIVE SHAFTS FOR BALL BUSHES

For a complete ball bush system the shaft should be considered as important as the inner race of a ball bush, so for high
performance and precision guidance the same level of technical characteristics are necessary. Therefore the shaft must be
made of the correct material, the heat treatment has to be done in the proper method. The grinding is the most important
factor to achieve the smooth and quiet running for the ball bushes. ASK has many years experience in the supply of shaft
for ball bush and supplies the high quality shaft so that the ball bushes can achieve the maximum performance.

Characteristic of Exclusive Shafts for Ball Bushes
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■High Reliability
As a background of technological strong for many years, exclusive shafts for ball
bushings have gained high reliability according to consistent management system from
material, heat treatment, straightening, grinding, lathe processing to testing and
shipment.

■Materials
High carbon chromium bearing steel or martensite stainless steels are used in the
manufacture of ASK ball bush shaft. As a guide for ball bushes, the surface of the
shaft contacting with the rolling steel balls is required to have a hardness of HRC 58-64. For durability against rolling
fatigue, the hardness must penetrate to a minimum depth of 1.5mm and the surface finish should be precision ground to a
minimum surface roughness of 0.8S~1.6S.

■Heat Treatment
In our many years experience in the induction hardening of ball bush shaft we have built up a significant amount of “know
how”that others find it difficult to match. ASK shafts have uniformity of hardness in both axial and circumferential
planes. For stability and straightness this is vital- uneven stresses result in bowed shaft. See diagrams below for typical cross
section of shaft with figure showing a typical micro hardness check across the same section.

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ACCURACY

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■Diameters of Shafts

According to the application or required clearance (or preload), the tolerance
of the shaft must be selected. For the special precise running, the shafts are
manufactured with the tolerance h5 shown in right table. By using the shaft
with h5 tolerance, the zero clearance or slight preload can be achieved.
At this time the user have to notice whether if there is no excessive preload
between shaft and ball bush by checking the smooth running of ball bush on
the shaft. If the bush cannot be moved on the shaft with the slight push by
hand then the preload is excessive. Excessive preload will lead to reduced life
expectancy.

■Deflection

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When large deflections occur along a shaft, the preload will take place
repeatedly and become a reason for short service life.
ASK has established deflection standard, shown at right table, to prevent
such preload, and the shafts will be finished by High grade if no special
precision is required.

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DOCUMENT FOR DESIGN

Calculation of Deflection

When the shaft is under load, the deflection occurs normally. In this case, the calculation formulas of reaction force,
sharing force, bending moment, deflection and inclination are shown follows.

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Shafts under Axial Load
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Example of Calculation for Deflection
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Example of Installation

Installation is really important in selecting diameters of shafts.
As a method of installation, typical instances are shown as follows. When installing 2 shafts parallel, install one shaft
correctly at first, and then use it as a basis to adjust the parallelism of another.
The distance between 2 shafts can be measured by micrometer or dial gauge.
Please pay a lot of attention so that an error of shaft installation will greatly influence the service life of shafts.

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