| 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. |
Precision Ground Ballscrews
Internal Ball Series
The advantage of internal ball circulation nut is that the outer diameter is smaller than that of external ball circulation nut. Hence it is suitable for the machine with limit space for Ballscrew installation.
It is strictly required that there is at least one end of screw shaft with complete threads. Also the rest area next to this complete thread must be with smaller diameter than the nominal diameter of the screw shaft.
Above are required for easy assembling the ballnut onto the screw shaft.
Dimension
End Deflector Series
It is important for a high-lead ballscrew to be with characteristics of high rigidity, low noise and thermal control. PMI takes its patented design and treatments to achieve the following characteristics:
High DN Value
Max. DN Value: 220,000
Low Noise
The average and accurate ball circle diameter (BCD) through whole threads make the ballscrews to obtain the stable and consistent drag torque as well as to reduce the noise. The audio frequency is low and deep due to the designed of plastic circulation system.
Space Saving
The ballnut diameter reduces 20%~25% substantially and the length of nut is shorter. The total space shall be reduced to approximately 50% consequently.
Circulation
The specially designed pathway of the Recirculation System makes a contact with lead angle and also with BCD in the same tangency, improving its smoothness eff ectively.
Applications
- CNC Machinery
- Precision Machinery
- High Speed Machinery
- Semi-Conductor Equipment
- Medical equipment
Dimension
External Ball Series
- Lower noise due to longer ball circulation paths.
- Offers smoother ball running.
- Offers better solution and quality for long lead or large diameter ballscrews.
Type
There are two types of Ballnut of the external circulation Ballscrews. They are “immersion type” of A and “extrusive type” of B. The “immersion type” means the ball circulation tubes are inside the circular surface of Ballnut as shown on specifi cations of this catalogue are of “immersion type”.
In some cases, as per designs on customer’s drawings, there are smaller outer diameters ballnuts required. Then the ball circulation tubes shall extrude out of Ballnut circular surface.
Dimension
High lead Series
High-lead Ballscrews are essential elements and parts for high-speed machine tools of next century.
It is important for a High-lead Ballscrew to be with characteristics of high rigidity, low noise and thermal control. PMI’s designs and treatments are taken for following:
High DN Value
The DN value can be 130,000 in normal case. For some special cases, for example in a fixed ends case, the DN value can be as high as 140,000. Please contact our engineers for this special application.
High Speed
PMI ‘s High-speed Ballscrews provide 100 m/min and even higher traverse speed for machine tools for high performance cutting.
High Rigidity
Both the screw and ballnut are surface hardened to a specific hardness and case depth to maintain high rigidity and durability.
Multiple thread starts are available to make more steel balls loaded in the ballnut for higher rigidity and durability.
Low Noise
Special design of ball circulation tubes offer smooth ball circulation inside the ballnut. It also makes safe ball fast running into the tubes without damaging the tubes.
Accurate ball circle diameter (BCD) through whole threads for consistent drag torque and low noise.
Dimension
Heavy Load Series
Focused on improvements of contact points of balls and thread grooves, ball diameter and circulation system for new type, FSVH. The rated dynamic load has been increased to as two times as that of conventional type, FSVC.
Long Life
Structure of the newly developed circulation system is designed to distribute the load uniformly to the load balls and it also increases the life of ballscrews.
On conventional circulation system, FSVC, the returning tube is inserted into the holes on ballnut perpendicularly which forms an advancing angle.
While ball moves into returning tube, it will hit tube end area and then move into returning tube. New circulation system, FSVH, ball will move into returning tube smoothly by tangent line as the same direction as lead angle. It can increase the life of circulation system structure.
High DN Value
With the newly developed circulation system, ballscrews can meet the demands of high speed running with high DN value.
Low Noise
To use tangential circulation system structure, it can eliminate the noise while balls run into the returning tube.
Various Specifications Combination
PMI can supply various ballscrews with diameter 50~100mm and lead 16mm to 25mm s
(Please contact PMI for your specifi c design requirement)
Recommend mounting direction of heavy load ball screws
In order to support equal load distribution for shaft and nut, recommend mounting direction of ball screws allow fig.1 This mounting direction can avoided vibration as axial load uneven distribution for ball screws, therefore increase service life efficient.
Fig.1 Recommend mounting direction of heavy load ballscrew
Fig. 2 Load distribution
Accuracy Grade and Axial Play
If you have any question about accuracy grade and axial play(e.g. axial play <0), please contact our sales for your specific design requirement.
Application
Plastic Injection Machines / Press and Forging Machines / Semi-conductor Equipments / General Machines
Dimension
End Cap Series
The back system is designed by the front and rear ends of cycle paths, with the nut on the through-hole as the ball back, so that all nuts are covered with bead groove ball so effectively in the same length under the nut, end plugs nuts than the outer cycle nut with higher dynamic loads.
Dimension
Miniature Series
For precision Miniature Ballscrew, PMI has reduced the Diameter of ballnut and used the special circulation system, to satisfy more stability and high precision requirement.
Space Saving
External circulation system, it don’t need to have at least one end with complete thread to the end of Ballscrew for Ballnut assembly to screw shaft. And the special design of ballnut, so the size of ballnut is same as internal circulation system of ballnut, Space saving.
Circulation
By way of 3D Spline designed pathway for circulation system, and has enhanced the smooth circulation of ball ,that can reduce the wearing and increase the life of ballscrew.
Application
Semiconductor equipments / Measuring devices / Inspection equipments / Nano-platform
Dimension
Rolled Ballscrews
Rolled Ballscrews
The production of the PMI rolled ballscrews has adopted a manufacturing process and equipment unlike other manufacturers. Combining advanced skills and the Bad Düben digital electric screw thread rolling machine, we adhere to a strict quality control policy at every stage of production, from the selection of ballscrew material and rolled processing to induction hardening heat treatment and post production. We are committed to providing clients with products of the best quality.
The combination of rolled ballscrews and ground nuts has replaced the traditional ACME screws and trapezoidal screws. This makes for a smoother operation while lowering friction and backlash. Moreover, the new technology has the advantage of faster production speed and lower prices.
Besides differences in the definition of lead deviation and geometric tolerance, rolled and ground ballscrews can both eliminate axial play by preloading. Please contact us for related technical information.
| Features | Nuts are Interchangeable |
| High Precision Rolled Nuts |
Dimension
Standard Models:
Optional Models:
| Lead Accuracy of Rolled Screws(e300) |  |
| Reference Table of the Nominal Outer Diameter and Lead of the PMI Rolled Screws | |
| Axial Play | |
| Material and Hardness | |
| Types and Dimensions of Rolled Screw Shaft | |
| Rolled Ballscrew Nuts | |
Ballscrews FA Series
The new circulation design of PMI FA series of precision ballscrews carried out the advantages of High Speed, Low Noise, Effi ciency, and Standardization for diff erent kinds of application.
| Features | Short Delivery |
| Flexibility of stroke length | |
| High accuracy with reasonable price | |
| Space saving | |
| High speed and lower noise |
Application range
Semiconductor equipments, Measuring devices, Inspection equipments, Medical equipments, Automation, Light load machining, Glue depositing, and other precision motion and positioning applications.
Dimension
