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 7.4.: Control knob

This example serves to practise straight knurling of convex parts.

Figure

Material

St 34 (St = steel, 34 = tensile strength up to 340 MPa)

Dimensions

dia. 44 x 65 mm

Working tools

Right-offset side-cutting tool, radius turning tool, chuck key, hollow (concave) knurling tool

Measuring and testing tools

Accessories

Hard chuck jaws, supporting plates, coolant and lubricant

Required previous knowledge

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

Explanations to the working drawing

 M 16: M = metric thread, 16 = nominal diameter Straight knurling K 1.0: K = hollow (concave) knurling wheel 1.0 = tooth pitch 1 mm

All surfaces finished.

 Sequence of operations Remarks 1. Dimensional inspection 2. Clamping of workpiece Chucking in hard chuck jaws 40 mm deep. 3. Clamping of tool to produce outside diameter Right-offset side-cutting tool. 4. Setting of cutting values 5. Producing the outside diameter t/2: d = 42 mm less 0.5 mm = 41.5 mm 6. Tool change for producing the radius Form turning tool to be selected according to radius of knurling tool. 7. Setting of cutting values Form turning tool is made of high-speed steel -v = 25 - 50 m/min.v = 25 m/min to be selected for form turning. 8. Producing the radius Radius turning tool to be in centre position. 9. Tool change for producing knurling Straight knurling tool to be clamped approx. 1 mm below centre and at right angle to workpiece axis. 10. Setting of cutting values v = 6 - 10 m/min, since concave knurling wheelv = 6 m/min to be selected. 11. Straight knurling of diameter To be cooled and lubricated with soluble oil or cutting oil. First knurling to be done with one feed setting, if possible.Tool to be positioned over full width - central position is essential Operation must not last longer than necessary since surface gets harder and more brittle because of pressure. 12. Deburring of edges of knurled portion Material is forced towards end faces forming burr. 13. Unloading of workpiece 14. Dimensional inspection Dimensional and visual inspection (cleanliness of knurling grooves).Knurling wheel to be cleaned by wire brush.

Figure