Knurling - Course: Techniques for Machining of Material. Instruction Examples for Practical Vocational Training: Instruction example 7.3.: Knurled screw

Knurling - Course: Techniques for Machining of Material. Instruction Examples for Practical Vocational Training

		(introduction...)
		Introduction
		Instruction example 7.1.: Locking screw
		Instruction example 7.2.: Ring thread gauge
		Instruction example 7.3.: Knurled screw
		Instruction example 7.4.: Control knob
		Instruction example 7.5.: Grip

Instruction example 7.3.: Knurled screw

This example serves to practise cross knurling of non-metallic materials.

Figure

Material

Thermosetting plastics

Dimensions

dia. 34 x 58 mm

Working tools

Right-bent roughing tool, chuck key, cross knurling tool with groove pitch 0.8 mm (used for hard rubber, plastics)

Measuring and testing tools

Vernier caliper

Accessories

Soft chuck jaws which can be internally turned, supporting plates, coolant and lubricant

Required previous knowledge

Reading of drawings, measuring and testing, behaviour of material in chipless shaping, internal turning of jaws, longitudinal turning and facing, use of coolants and lubricants

Explanations to the working drawing

M 12:	M = metric thread, 12 = nominal diameter
R 3:	3 mm radius
Cross knurling 0.8:	Cross knurling = tooth pitch crossing at 90°, 0.8 = tooth pitch of 0.8 mm

All surfaces finished.

Sequence of operations		Remarks

1.	Dimensional inspection

2.	Clamping of workpiece	Chucking - soft chuck jaws to be internally turned for dia. 12 mm.

3.	Clamping of tool to produce knurling diameter	Right-bent roughing tool.

4.	Setting of cutting values

5.	Producing the knurling diameter	t/2: d = 32 mm less 0.4 mm = 31.6 mm

6.	Tool change for producing knurling	Cross knurling tool to be clamped approx. 1 mm below centre and at right angle to workpiece axis.

7.	Setting of cutting values for cross knurling	v = 6 - 10 m/min - since soft material v = 10 m/min to be selected.

8.	Cross knurling of diameter	To be cooled and lubricated with diluted soluble oil or petroleum.

9.	Tool change for chamfering	Right-bent roughing tool

10.	Chamfering of workpiece	Chamfers 0.8 x 45° each (chamfer = t). Chamfering after knurling because material is also forced towards end faces. v like for turning of outside diameter

11.	Unloading of workpiece

12.	Dimensional inspection	Dimensional and visual inspection (cleanliness of grooves). Cross knurling wheel to be cleaned by wire brush.

Figure