1964_IMPORT_AND_EXPORT_(STRATEGIC_COMMODITIES)_REGULATIONS — Page 18

G 18

CAP. 60]

Import and Export (Strategic Commodities) Regulations

[1988 Ed.

[Subsidiary]

3.

4.

IL 1093

IL 1110

For computer-related terms, see Item IL 1565 or IL 1566.

A "direct numerical control system" (DNC) is defined as "a system connecting a set of numerically controlled machines to a common memory for part programme or machine programme storage with provision for on-demand distribution of data to the machines" (Ref. ISO/DIS 2806.2).

5. Axis nomenclature shall be in accordance with international standard ISO 841, "Numerical Control Machines-Axis and Motion Nomenclature".

6. The value of the positioning accuracy does not include the width of backlash. The value is determined by the usual statistical methods (random tests); i.e. by approaching from only one direction of a minimum of 5 measurement points up to a maximum of 25 measurement positions as random tests along one axis. National standards may be used for this measuring method; e.g. the German standard VDI "Statistical testing of the operational and positioning accuracy of machine-tools VDI-DGQ3441, March, 1977".

7.

A tilting axis is defined as an axis which alters the angular position of the rotary table centreline with respect to the spindle centreline during the machining process.

Components and specially-designed parts for machine tools and dimensional inspection machines embargoed by Item IL 1091, as follows:

(a) Spindle assemblies, consisting of spindles and bearings as a minimal assembly, except those assemblies with axial and radial axis motion measured along the spindle axis in one revolution of the spindle equal to or greater (coarser) than the following:

(i) 0.0008 mm TIR (peak-to-peak) for lathes and turning machines; or

(ii) D×2×10−5 mm TIR (peak-to-peak), where D is the spindle diameter in millimetres, for milling machines, boring mills, jig grinders, and machining centres;

(b) Lead screws, including ball/nut screws, except those having all of the following characteristics:

(i) Accuracy equal to or greater (coarser) than 0.004 mm/300 mm;

(ii) Overall accuracy equal to or greater (coarser) than (0.0025+45 × 10−6 × L) mm, where L is the effective length in millimetres of the screw;

(iii) Concentricity of the centre line of the journal bearing surface and the centre line of the major diameter of the screw equal to or greater (coarser) than 0.005 mm TIR (peak-to-peak) at a distance of three times the diameter of the screw or less from the journal bearing surface;

(c) Linear and rotary position feedback units including inductive type devices, graduated scales, and laser systems, except:

(i) Linear types having an accuracy equal to or greater (coarser) than (0.0004+13 × 10−6×L) mm, for L equal to or less than 100 mm and (0.0015+2×10−6×L) mm, for L greater than 100 mm, where L is the effective length in millimetres of the linear measurement; and

(ii) Rotary types having an accuracy equal to or greater (coarser) than two seconds of arc;

(d) Linear induction motors used as drives for slides, having all the following characteristics:

(1) Stroke greater than 200 mm;

(2) Nominal force rating greater than 45 N;

(3) Minimum controlled incremental movement less than 0.001 mm

GROUP B

CHEMICAL AND PETROLEUM EQUIPMENT

Equipment for the production of liquid fluorine, and specially designed components therefor.