PMI ball screw characteristics
High reliability
PMI has accumulated many years experience in production managing. It covers the whole production sequence, from receiving the order, designing, material preparation, machining, heat treating, grinding, assembling, inspection, packaging and delivery. The systemized managing ensures high reliability of PMI Ballscrews.
High accuracy
PMI Ballscrews are machined, ground, assembled and Q.C. inspected under the constant temperature control (20℃) to ensure high precision of Ballscrews. accuracy inspection certifi cate.
Long durability
PMI Ballscrews are made of German Alloy steels, which are well quenching and
tempering treated for good rigidity, along with suitable surface hardening to ensure long durability.
High working
efficiency
Balls are rotating inside the Ballscrew nut to offer high working efficiency.
Comparing with the traditional ACME screws, which work by friction sliding between the nut and screw, the Ballscrews needs only 1/3 of driving torque.
It is easy to transmit linear motion into rotation motion.
No backlash and with high rigidity
The Gothic profile is applied by PMI Ballscrews. It offers best contact between
balls and the grooves. If suitable preload is exerted on Ballscrew hence to eliminate clearance between the ball nut and screw and to reduce elastic deformation, the ballscrew shall get much better rigidity and accuracy.
PMI's precision ground Ballscrews are controlled in accordance with JIS B 1192.
The permissible values and each part of defi nitions are shown below.
Terms
| T+E |
Cumulative representative lead.
A straight line representing the tendency of the cumulative actual lead.
This is obtained by least square method and measured by laser system. |
| P |
Permissible value. |
| a |
Actual value. |
| T |
Specifi ed travel.
This value is determined by customer and maker as it depends on different application
requirements. |
| E |
Accumulated reference lead deviation.
This is allowable deviation of specifi ed travel. It is decided by both of the accuracy grade and
effective thread length. |
| e |
Total relative lead variation
Maximum width of variation over the travel length. |
| e300 |
Lead deviation in random 300 mm. |
| e2π |
Lead deviation in random 1 revolution 2π rad. |
Accumulated reference lead deviation (±E) and total relative variation (e)
Unit：μm
| ffective thread length (mm) |
GRADE |
Co |
C1 |
C2 |
C3 |
C4 |
C5 |
| OVER |
UP TO |
E |
e |
E |
e |
E |
e |
E |
e |
E |
e |
E |
e |
| |
315 |
4 |
3.5 |
6 |
5 |
8 |
7 |
12 |
8 |
12 |
12 |
23 |
18 |
| 315 |
400 |
5 |
3.5 |
7 |
5 |
9 |
7 |
13 |
10 |
14 |
12 |
25 |
20 |
| 400 |
500 |
6 |
4 |
8 |
5 |
10 |
7 |
15 |
10 |
16 |
12 |
27 |
20 |
| 500 |
630 |
6 |
4 |
9 |
6 |
11 |
8 |
16 |
12 |
18 |
14 |
30 |
23 |
| 630 |
800 |
7 |
5 |
10 |
7 |
13 |
9 |
18 |
13 |
20 |
14 |
35 |
25 |
| 800 |
1000 |
8 |
6 |
11 |
8 |
15 |
10 |
21 |
15 |
22 |
16 |
40 |
27 |
| 1000 |
1250 |
9 |
6 |
13 |
9 |
18 |
11 |
24 |
16 |
25 |
18 |
46 |
30 |
| 1250 |
1600 |
11 |
7 |
15 |
10 |
21 |
13 |
29 |
18 |
29 |
20 |
54 |
35 |
| 1600 |
2000 |
|
|
18 |
11 |
25 |
15 |
35 |
21 |
35 |
22 |
65 |
40 |
| 2000 |
2500 |
|
|
22 |
13 |
30 |
18 |
41 |
24 |
41 |
25 |
77 |
46 |
| 2500 |
3150 |
|
|
26 |
15 |
36 |
21 |
50 |
29 |
50 |
29 |
93 |
54 |
| 3150 |
4000 |
|
|
32 |
18 |
44 |
25 |
60 |
35 |
62 |
35 |
115 |
65 |
| 4000 |
5000 |
|
|
|
|
52 |
30 |
72 |
41 |
76 |
41 |
140 |
77 |
| 5000 |
6300 |
|
|
|
|
65 |
36 |
90 |
50 |
95 |
50 |
170 |
93 |
| 6300 |
8000 |
|
|
|
|
|
|
110 |
62 |
120 |
62 |
210 |
115 |
| 8000 |
10000 |
|
|
|
|
|
|
|
|
157 |
75 |
260 |
140 |
