LINEAR MOVEMENT SOLUTIONS
Tailored solutions for linear movement
Our completely custom movement solutions can be cost-efficiently tailored in terms of every detail, such as strength, accuracy, noise level, lifetime and footprint.
Most common solutions for linear motion mechanisms are motion screws, rack and pinion solutions and belt drives.
CUSTOMIZED STROKE AND SPEED
LINEAR FORCE UP TO
35 000 N
ACCURACY > 1 µm
TAILORED IP RATING
TAILORED NOISE LEVEL
Ball screws use ball bearings to eliminate the friction between the nut and the screw, making the mechanism more efficient. As a result, the efficiency of the ball screw will be as high as 96 %.
Ball screws can achieve high accuracy, smooth movement, high wear resistance and significantly higher efficiency under high load ratings than lead screws.
As a disadvantage, the ball screw mechanism is more expensive compared to lead screws. Ball screws also require lubrication, which may cause issues in clean environments, such as with medical and food processing applications.
Ball screw properties:
- High accuracy for positioning
- Smooth movement
- High load ratings in dynamic applications
- High efficiency
- Low drive power requirements
- Low self-heating due to low friction
- High lifetime with minimum need for maintenance
Lead screws are based on a helical screw with a mating nut. Compared to ball bearings, the sliding contact causes more friction, so lead screws are generally less efficient and less accurate than ball screws. For this reason, lead screws are commonly used in less demanding applications, and they are not optimal for high-throughput, high-speed or continuous movement applications.
However, the friction coefficient depends heavily on the materials of the screw and the nut. For example, when using nut materials containing lubrication additives, such as plastic, no additional external lubrication is needed. That makes the lead screw an ideal solution for clean environment applications.
As a disadvantage, a structure-specific “stick-lip” may cause problems with precise motion solutions, due to the difference between rest friction and motion friction.
Lead screw properties:
- Small to medium load ratings
- Tailored materials and coatings
- Self-locking mechanism
- Low noise level
How to choose the right motion screw type?
In general, ball screws are a better choice for applications requiring smooth motion, efficiency, accuracy, precision and prolonged continuous or high-speed movement.
On the other hand, traditional lead screws are more suitable for transfer applications, where speed, accuracy and precision do not play a critical role.
There are various other requirements for a movement solution, such as noise level, footprint, wobbling, external conditions and expected lifetime. Still, in most cases, the initial evaluation of load and accuracy requirements gives adequate guidelines for choosing the right solution.
Tasowheel manufacturing process
Tasowheel manufactures screws by grinding, so the manufacturing method does not set any limitations for the screw design. The thread can be machined exactly to the desired position with the desired length, and the screw can be integrated into the actuator components if needed.
Grinding as a manufacturing method enables a smaller pitch error and minimized movement clearance, thus optimizing movement accuracy. In addition, manufacturing the screw by grinding allows the use of particularly hard materials, which cannot be produced by rolling. When using grinding, the final shape can also be machined into a pre-hardened part.
In addition, grinding enables the manufacturing of special shapes, as the manufacturing method does not limit the optimal design of the motion solution.
Tasowheel can manufacture screws up to 200 mm in diameter, and up to 600 mm in length.
Rack and pinion drive
Rack and pinion drives are often overlooked as past-generation technology with limited motion and positioning accuracy, but this is not the case.
The performance of rack and pinion solutions has improved by using high-end machining, grinding and surface finishing solutions.
Rack and pinion systems can offer smooth movement, superior positioning accuracy and unlimited travel distance in a compact size at reasonable costs.
Regarding acceleration and speed, the rack and pinion systems allow faster movements and higher speeds than motion screws, which may begin to suffer vibration, a so-called “screw whip”, at higher speeds. For the same reason, the motion screws are not optimal for longer travel distances with long spans between bearing supports.
Rack and pinion solutions are also extremely resilient to contamination in harsh environments. With adequate lubrication, the rack and pinion systems can last for hundreds of millions of cycles before needing replacement.
Rack & pinion properties:
- Cost-efficient solution
- Simple and robust design
- Compact size
- Modern machining allows high performance and precision
- Allows high acceleration and speeds
- High efficiency
- Long lifetime
Belt driven actuators convert rotary motion to linear motion by utilizing a timing belt connected between two pulleys at either end of the drive. The timing belt is typically constructed of a fibre-reinforced elastomer for light-duty applications, or steel-reinforced polyurethane for more demanding requirements. It contains teeth that mesh with pulleys to prevent slipping.
Due to high efficiency and simplicity, the belt-driven actuators are a good choice for long-stroke applications with lower loads, especially when high speeds are needed. On the other hand, belt drives cannot transfer high loads or achieve high accuracy and repeatability over time due to the stretching of the belt.
Belt drive properties:
- Long travel distances
- High efficiency
- Not suitable for high loads
- Need for maintenance