Industrial Use for Diamonds

Manawatu Times, Volume 62, Issue 26, 1 February 1937, Page 10

Industrial Use for Diamonds

COMPARATIVE FEW MADE INTO ORNAMENTS

LONDON, Jan. 2. Nearly a ton of diamonds, chiefly of inferior grades, is consumed industrially every year. Largo quantities, in fact, are used for industrial purposes than for personal adornment. Tho bulletin of the Imperial Institute states that in recent years at least 60 per cent, by weight of the world’s outI put has been of stones suitable only for industrial purposes. Whereas the gem diamond is mainly preserved, the industrial diamond is consumed. In view of its hardness, the industrial diamond is chiefly used for abftsive purposes, mainly in the form of tools of various kinds, including the crowns of core-drills, as well as in the form of dust for lapping. Tho dust may also bo bonded and moulded into abrasive wheels. Dimonds are also employed for the reverse purpose, namely, to withstand abrasion by other substances, notably in the form of draw-plates or dies for wire-drawing, and as jets for oil-burning furnaces. The majority consumed annually (probably 40 per cent.) are used in the form of diamond-tipped tools for trying up abrasive wheels made of emery, carborundum, and such substances, of which largo numbers are employed by engineering firms for precision grinding. Diamond-Pointed Tools Diamond-pointed tools arc being used to an increasing extent for tho accurate machining of many nonferous metals and alloys, as well as of ebonite and synthetic resins, such as bakelite. In tho motor manufacturing industry, for instance, they are used for tlio machining of big-end bearings and aluminium alloy pistons. Tho durability of the points of these tools permits of much saving of time, as they enable repetition work to be caried out for long periods without re-settiug the machine. Tho technique of manufacture of dia-mond-set tools is rapidly advancing. Diamond dies are widely used in wire-drawing, especially for very fine wires, and this use probably accounts for about 20 per cent, of tho consumption. The cutting of building stones is quickly done with steel circular saws carrying diamonds around the nm. A large saw of this type, 7ft in diameter, which would have more than 1000 dia-‘ monds embedded in its edge, has a life of some 2500 sawing hours before the stones need resetting. A new and superior type of cutting or grinding wheel incorporating crushed diamond is shortly to be manufactured commercially.

The Union of South Africa has long been tho principal producer of diamonds for gem purposes, but the quantity of industrial diamonds produced there has been greatly reduced for several years past. On tho other hand, tho greatly increased diamond output of the Belgian Congo and Angola consists largely of stones unsuitable for jewellery and these countries provide most of the world’s industrial diamonds. A proportion of tho stones from Woet Africa and Borneo are also of industrial grade.

son, four for 16, Ross, one for 20, J. Gallichan, none for 13. UNITED First Innings A. S. H. Cutler, b Rabone 53 Spiers, retired (hurt) 7 Pollitt, not out .. 27 Lynch, stpd Gatley, b Rabone, .. 5 Ross,n ot out 13 Extras .. 6 Total for two wickets .. .. 11l SENIOR B. City secured four points as a result of their match with Kia Toa. On the opening day City made 88 and Kia Toa 52, tho drawing of stumps finding tho former with four down for seven in their second strike. When the game was resumed, City carried their score to 95 (Burgess 42). Morgan took four for 17 and Piercey three for nine. Kia Ton’s second strike was productive of 49, Brown top-scoring with 18. Weston secured three for seven, Lovejoy two for nine and Baigent two for 17. Y.M.O.A. (120 and 116 for 5 wickets) defeated H. L. Young’s (147 and 84). McKenzie (18) was top scorer in H. L. Young’s second innings, in which Hornabrook took four for 28 and McMinn three for 25. Hornabrook (46) and Shaw (26 not out) wore the chief contributors in Y.M.C.A. ’s second strike. Hart secured two for 15.

Holding an advantage on tho first innings, Combined Services fought hard to avoid an outright win by Old Boys, but were all out half-an-hour before the time for the pulling of stumps. On the opending day Old Boys’ first strike was productive of 50, to which Combined Services replied with 55. When play was adjourned, Old Boys had scored 132 for the loss of five wickets and on the game being resumed, carried the total to 206 ( Trow 40). B. Millar took five for 65. Combined Services, in their second innings, were dismissed for 146 (Hancock 57, B. Millar 28, Winks 23). Trow was the most successful bowler, taking four for 31. JUNIOR A. Old Boys secured a four-point win over Combined Services. The previous Saturday the latter were dismissed in their first strike for 35, while Old Boys put together 99. When the game was resumed, Combined Services made 315 in their second innings, and Old iLiys knocked up the requisite 51 runs for tho loss of five wickets. Bowling for Old Boys, Waldcgravo took five for 60. GAME AT TERRACE END la a friendly game played at Terraco End, Optimists 184 (Summerville 67 uot out, Waugh 23, Cooper 22, R. Zaloum 19) beat United 145 (Bluelts 42, Barker 24, Sloraau 17, Ward 16, Burne 13).