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 7.1.: Locking screw

This example serves to practise straight knurling of simple cylindrical parts.

Figure

Material

St 42 (steel with tensile strength up to 420 MPa)

Dimensions

dia. 62 x 110 mm

Working tools

Right-bent roughing tool, chuck key, straight knurling tool with straight pitch (t = 0.8 mm)

Measuring and testing tools

Vernier caliper

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 0.8: straight knurling = straight wheel 0.8 = tooth pitch 0.8 mm

 Sequence of operations Remarks 1. Dimensional inspection dia. 30 x 14 mm 2. Clamping of workpiece Chucking - chuck jaws to chuck on dia. 16 mm, 30 mm deep. 3. Clamping of tool to produce knurling diameter Right-bent roughing tool 4. Setting of cutting values for turning the outside diameter For steel v = 80 m/min.Surface finished. 5. Producing the knurling diameter By experience it is known that diameter of finished part becomes bigger by approx. half the pitch (1/2 mm) of knurling tool, i.e. diameter to be turned smaller - d = 30 mm less 0.4 mm = 29.6 mm. 6. Tool change for producing knurling Width of knurling tool according to width of workpiece.Knurling tool to be clamped approx. 1 mm below centre and at right angle to workpiece axis. 7. Setting of cutting values for straight knurling For steel v = 6 to 10 m/min.For St 42 v a 10 m/min to be selected. 8. Straight knurling of diameter To be cooled and lubricated with diluted soluble oil or cutting oil (heavy pressing force results in high friction and heat). 9. Tool change for producing the chamfers Right-bent roughing tool. 10. Chamfering of workpiece Chamfering of workpiece after knurling is necessary because material is forced towards end faces, both ends 0.8 x 45° (chamfer = t). 11. Unloading of workpiece 12. Dimensional inspection Dimensional and visual inspection (cleanliness of knurling grooves). Wheel of knurling tool to be cleaned by wire brush.

Figure