120-Mesh Sieve: U.S. Standard Sieve No. 120 (Bureau of Standards, 1924)

The standard testing sieve No. 120: plain-woven brass or bronze wire cloth with 0.125 mm (0.0049 in) openings and 0.086 mm (0.0034 in) wire, soldered smoothly into a round frame about 20 cm (8 in) across. Result: a sieve that passes grains under 0.125 mm and holds back larger ones, made to the Bureau of Standards tolerances. Source: Bureau of Standards, Letter Circular 74, Standard Specifications for Sieves (revised 1924). Unknown: the frame metal and the weaving. Picture: the Bureau's table.

متوسط

Unknown

التعليمات

Weave the wire cloth

Weave plain (not twilled) cloth from brass, bronze or other suitable wire 0.086 mm (0.0034 in) thick, so the openings between adjacent wires are 0.125 mm (0.0049 in) each way, about 120 wires to the inch. Ours: bronze wire. Not given: how it is woven.

المواد لهذه الخطوة:

سلك برونزي1 warp and shoot wires

الأدوات المطلوبة:

نول نسيج الأسلاك

Make the frame

Make a circular frame about 20 cm (8 in) across, with about 5 cm (2 in), or 2.5 cm (1 in), between its top and the cloth. Ours: brass strip. Not given: the frame metal.

المواد لهذه الخطوة:

شريط نحاس أصفر1 frame

الأدوات المطلوبة:

مقصّ صفائح

كاوية لحام

Mount the cloth

Mount the cloth on the frame without distorting it. Fill the joint between cloth and frame smoothly with solder, so the material being sieved cannot catch in it.

المواد لهذه الخطوة:

لحام قصدير-رصاص1 joint

مساعد صهر1 joint

الأدوات المطلوبة:

كاوية لحام

Check it against the tolerances

Measure the warp and shoot wires separately. Their average opening must be 0.125 mm within ±6 %, their average diameter 0.086 mm within −15 to +35 %, and no opening may exceed 0.125 mm by more than 40 %. Reject a sieve with punctures, loose or wavy cloth, poor soldering, or too many large openings.

الأدوات المطلوبة: