Change Nut

The Change Nut Models DCMA and DCMB have a lead angle of 45°, which is difficult to achieve through machining. Each model is capable of converting linear motion into rotary motion, or vice-versa, at high efficiency. Because of the large leads, they are optimal for providing a fast-feed mechanism at low-speed rotation. The multi-thread screw shafts to be combined with these change nuts are formed through cold gear rolling. The surface of the teeth is hardened to over 250 HV and mirror-finished. As a result, the shafts are highly wear-resistant and achieve significantly smooth motion when used in combination with these change nuts. Models DCMA40, DCMB40, or higher are designed for use in combination with cut screw shafts.
Miniature change nuts are made of an oil-impregnated plastic,
enabling them to have wear resistance and excel in lubrication especially in an oil-less operation. In addition, since the high level of their performance can be maintained for a long period, they enable long-term maintenance-free operation.

Precautions on Use

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Wear resistance

Features

Structure and Features

The Change Nut models DCMA and DCMB have a lead angle of 45°, which is diffi cult to achieve through machining. Each model is capable of converting a straight motion to a rotary motion, or a vise versa, at high efficiency. Because of the large leads, they are optimal for providing a fast feed mechanism at a lowspeed rotation. The multi-thread screw shafts to be combined with these change nuts are formed through cold gear rolling. The surface of the teeth is hardened to over 250 HV and mirror-finished. As a result, the shafts are highly wear resistant and achieve significantly smooth motion when used in combination with these change nuts. Models DCMA40, DCMB40 or higher are designed for use in combination with the cut screw shafts. The Miniature Change Nuts are made of an oil-impregnated plastic, and have a wear resistance and excel in lubrication especially in an oil-less operation. In addition, since the high level of their performances can be maintained for a long period, they allow long-term maintenance-free operation.

Features of the Special Rolled Shafts

Dedicated rolled shafts with the standardized lengths are available for the Change Nut.

Increased Wear Resistance

The shaft teeth are formed by cold gear rolling, and the tooth surface is hardened to over 250 HV and mirror-finished. As a result, the shafts are highly wear resistant and achieve significantly smooth motion when used in combination with the nuts.

Improved Mechanical Properties

Inside the teeth of the rolled shaft, a fi ber fl ow occurs along the contour of the tooth surface of the shaft, making the structure around the teeth roots dense. As a result, the fatigue strength is increased.

Additional Machining of the Shaft End Support

Since each shaft is rolled, additional machining of the support bearing of the shaft end can easily be performed by lathing or milling.

High Strength Zinc Alloy

The high strength zinc alloy used in the change nuts is a material that is highly resistant to seizure and the wear and has a high load carrying capacity. Information on mechanical properties, physical properties, and wear resistance is presented below.

*The figures shown are target values—these figures are not guaranteed.

Mechanical Properties

Table1

Item	Description
Tensile strength	275 to 314 N/mm²
Tensile yield strength (0.2%)	216 to 245 N/mm²
Compressive strength	539 to 686 N/mm²
Compressive yield strength (0.2%)	294 to 343 N/mm²
Fatigue strength	132 N/mm²×10⁷ (Schenk bending test)
Charpy impact	0.098 to 0.49 N･m/mm²
Elongation	1 to 5 %
Hardness	120 to 145 HV

Physical Properties

Table2

Item	Description
Specifi c gravity	6.8
Specifi c heat	460 J/(kg･K)
Melting point	390 ℃
Thermal expansion coeffi cient	24×10^-6

Wear Resistance

Table3 [Test conditions: Amsler wear-tester]

Item	Description
Test piece rotational speed	185 min^-1
Load	392 N
Lubricant	Dynamo oil