Acme Screw Assembly

Note: when the thread is left hand, it needs to mark “L” behind specification, while it needn’t for right hand thread.

Pitch tolerance and accumulated pitch tolerance of acme screw

Accuracy Grade	Pitch Tolerance	Accumulated Pitch Tolerance within the following length (mm)		Accumulated Pitch Tolerance within the following thread length (mm)
Accuracy Grade	Pitch Tolerance	≤60	≤300	≤1000	≤2000	≤3000	≤4000	≤5000	＞5000ncrease correspondingly with per added 1000
3	0.9	1.2	1.8	2.5	4	-	-	-	-
4	1.5	2	3	4	6	8	12	-	-
5	2.5	3.5	4.5	6.5	10	14	19	-	-
6	4	7	8	11	16	21	27	33	39
7	6	10	18	28	36	44	52	60	8
8	12	20	35	55	65	75	85	95	10
9	25	40	70	110	130	150	170	190	20

Pitch and nominal diameter of

Pitch	3	4	5	6	8	10	12	16	20
Acme Screw	10-60	16-80	22-100	30-100	22-100	30-100	30-100	44-100	85-100

Effective length of acme screw thread
Calculation formula for effective length Lu of screw thread: Lu=L-2Le-----（A）Herein: L- length of screw thread

Le- (see attached Figure A and Attached List A)

Pitch P	2	3	4	5	6	8	10	12	16	20
Yu Cheng Le	10	12	16	20	24	32	40	45	50	60

Standard bolt

Standard Specification	M12	M14	M16	M18	M20	M22	M24	M27	M30	M33	M36	M39	M42	M45	M48	M52	M56	M64
Pitch	1.75	2 1.5	2 1.5	2.5 2	2.5 2	2.5 2	3 2	3 2	3.5	3.5 2.5	4 3.2	4 3.2	4.5 4 3	4.5 4	5 4	5 4	5.5 4	6 4

Screw process quality standard

1. The raw materials of screw is to the required pitch diameter. The secondary cold drawn surface hardness can reach （18°-21°）
2. The screw are in compliance with standard of GB5796.4-1986
3. Screw accuracy: Grade 3 to Grade 4
4. The cold pressed screw is made by aligning the raw materials, and its surface hardness (depth of 0.5mm) can reach 22°.
5. The screw is treated with hard chromium and polished and then aligned before outgoing.
6. The screw will be fabricated according to customer’s requirements.
　　Our company has dedicated lathe for precise screw and can produce standard and special type screw together with

allocation of various cast iron and copper nut. We can produce professionally and welcome processing with supplied designs and drawings.