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The so-called white metals are employed almost exclusively for bearings. (See Anti-friction Metals under Alloys.) In the technology of mechanics an accurate distinction is made between the different kinds of metals for bearings; and they may be classed in two groups, red brass and white metal. The {79} red-brass bearings are characterized by great hardness and power of resistance, and are principally used for bearings of heavily loaded and rapidly revolving axles. For the axles of large and heavy flywheels, revolving at great speed, bearings of red brass are preferable to white metal, though more expensive.

In recent years many machinists have found it advantageous to substitute for the soft alloys generally in use for bearings a metal almost as hard as the axle itself. Phosphor bronze (q. v.) is frequently employed for this purpose, as it can easily be made as hard as wrought or cast steel. In this case the metal is used in a thin layer, and serves only, as it were, to fill out the small interstices caused by wear on the axle and bearing, the latter being usually made of some rather easily fusible alloy of lead and tin. Such bearings are very durable, but expensive, and can only be used for large machines. For small machines, running gently and uniformly, white-metal bearings are preferred, and do excellent work, if the axle is not too heavily loaded. For axles which have a high rate of revolution, bearings made of quite hard metals are chosen, and with proper care—which, indeed, must be given to bearings of any material—they will last for a long time without needing repair.

WHITE METAL FOR BEARING.
	Tin	Antimony	Zinc	Iron	Lead	Copper
I	German, light loads	85.00	10.00	—	—	—	5.00
II	German, light loads	82.00	11.00	—	—	—	7.00
III	German, light loads	80.00	12.00	—	—	—	8.00
IV	German, light loads	76.00	17.00	—	—	—	7.00
V	German, light loads	3.00	1.00	5.00	—	3.00	1.00
VI	German, heavy loads	90.00	8.00	—	—	—	2.00
VII	German, heavy loads	86.81	7.62	—	—	—	5.57
VIII	English, heavy loads	17.47	—	76.14	—	—	5.62
IX	English, medium loads	76.70	15.50	—	—	—	7.80
X	English, medium loads	72.00	26.00	—	—	—	2.00
XI	For mills	15.00	—	40.00	—	42.00	3.00
XII	For mills	—	1.00	5.00	—	5.00	—
XIII	For mills	—	1.00	10.00	—	2.00	—
XIV	Heavy axles	72.70	18.20	—	—	—	9.10
XV	Heavy axles	38.00	6.00	47.00	—	4.00	1.00
XVI	Rapidly revolving axles	17.00	77.00	—	—	—	6.00
XVII	Very hard metal	55.00	—	—	70.00	—	2.50
XVIII	Very hard metal	12.00	82.00	2.00	—	—	4.00
XIX	Cheap metal	2.00	2.00	88.00	—	—	8.00
XX	Cheap metal	1.50	1.50	90.00	—	—	7.00

Other white bearing metals are:

XXI.—Tin, 8.5; antimony, 10; copper, 5 parts.

XXII.—Tin, 42; antimony, 16; lead, 42 parts.

XXIII.—Tin, 72; antimony, 26; copper, 2 parts.

XXIV.—Tin, 81; antimony, 12.5; copper, 6.5 parts.