BS 1983-5:1989

Foreword
Committees responsible
Code of practice
1 Scope
2 Chuck grip
2.1 General
2.2 Forces applied to the chuck
2.3 Change of grip at speed
2.4 Achieving the required grip
2.5 Flexible workpieces
3 Maximum speed of the chuck
4 Balancing
5 Inertia loading imposed on the drive
6 Gravitational and cutting forces; effect on the
     machine
7 Other aspects of the safe operation of lathe chucks
7.1 Chuck keys
7.2 Gross overspeeding
7.3 Adaptors
7.4 Mounting bolts for chuck body
7.5 Mounting bolts for jaws
7.6 Jaw materials
7.7 Dissipation of kinetic energy
7.8 Stroke detectors
7.9 End of bar detectors
8 Summary of the responsibilities of machine tool
     manufacturer, chuck manufacturer and user
Appendices
A Estimation of power available at the cutting zone
B Radial stiffness and out-of-roundness of ring held
     in jaws
C Measurement of the inertia of irregular components
D Worked example
Tables
1 Typical value of density, rho
2 Specific cutting forces, ks, for turning, facing
     and boring
3 Work material factor, k, for drilling (and deep
     hole boring) torque
4 Work material factor, kf, for drilling (and deep
     hole boring) feed
5 Value of work material factor, k, for tapping
6 Values of tap factor, Ct
7 Values of thread depth factor, Cd, for tapping
8 Values of thread factor, Cm, for tapping
9 Experimentally determined gripping coefficient,
     mu sp (mandrel chuck) (taken from VDI 3106)
10 Maximum peripheral speeds for various diameters of
     chuck bodies
11 Radii of gyration and moments of inertia
12 Typical values of inertia for chucks where jaws are
     outwardly offset and lie flush against the outside
     diameter
13 Values of k delta and k (delta - delta')
Figures
1 External forces: horizontal spindle, overhung
     workpiece
2 External forces: vertical spindle
3 External forces: inclined slide
4 Feed rate v. torque factor Cs: drilling
5 Feed rate v. feed force factor Fs1 (for drills up
     to 16 mm diameter in steel and cast iron and for
     all drill sizes in brass and aluminium)
6 Feed rate v. feed force factor Fs1 (for drills
     16 mm diameter and larger, in steel and cast iron)
7 Multiplying factors when tailstock centre is used
8 Typical curve showing change of grip with speed
9 'Standard' jaw positions
10 Calculation of change of grip at speed
11 Calculation of change of grip at speed: flexible
     workpieces
12 Graph of change of grip v. stiffness ratio for a
     flexible workpiece
13 Maximum residual specific unbalance
14 Typical output from a velocity transducer (mounted
     transversely on a headstock)
15 Loads applied to spindle
16 Clamping on to a thin ring: multiple jaws
17 Trifilar suspension
18 Sketch of component
19 Permitted mass x eccentricity v. spindle speed
20 Inertia load permitted
21 Lathe spindle data
22 Chuck: leading dimensions and data
23 Change of grip with speed (external grip)
24 Total grip v. drawbar pull
25 Radial deflection v. total grip
26 Forces applied to chuck
27 Loading on chuck (2nd operation) (turning and
     facing)
28 Loading on chuck and spindle (1st operation)

Safe practices for design and operation of power and manually operated workholding chucks used on turning machines

This Part of BS 1983 identifies and describes safe practices for design operation of workholding chucks used on turning machines.

The technical aspects covered by this code concern:

1. the adequacy of the gripping force in the chuck;
2. the fact that at excessive speed there may be failure of chuck components (fracture or excessive yielding);
3. acceptable degrees of lack of balance and consequent vibration;
4. the inertia loading imposed on the machine drive both by the chuck and by the workpiece;
5. gravitational forces arising from the mass of the chuck and workpiece, together in some circumstances with cutting forces, and their effect on the machine;
6. other aspects concerning the safe operation of lathe chucks.

Whilst primarily intended for application to lever and wedge type power chucks, including centrifugally compensated types, this code of practice can and should also be applied to manual chucks, but in such cases it is necessary to know the input torque.

NOTE 1 It should be recognized that even when a torque wrench or power driver is used, the grip is known to a lesser accuracy than, say, that of a power chuck having an hydraulically operated drawbar.

NOTE 2 The titles of the publications referred to in this standard are listed on the inside back cover.