How to choose the right screw jack in 10 steps

1. First Step: Choose the right type of screw jack

Depending on the requirements and parameters you have identified, there are different types of screw jacks to choose from:

1. Screw Jacks: Suitable for applications where high precision and load stability are required. They typically offer slow, accurate movement.
2. High-performance Screw Jack: These gearboxes are well-suited for applications that require a high gear ratio and high load-bearing capacity.
3. High-speed Screw Jack: Ideal for linear movements requiring high speed and precision.

2. Second Step: Understand your requirements and parameters

First, clarify the purpose of the screw jack. What functions and performance characteristics are needed? Before searching for the right screw jack, you need to fully understand your requirements and the necessary parameters. These include:

1. Load Capacity: Determine the weight or load that the screw jack needs to move or support. Additionally, check the static and dynamic load capacities. For example, if your system needs to hold and move a force of 7.5 kN, the MJ2 screw jack, which can handle up to 10 kN, would be sufficient. The dynamic performance limit also comes into play. An MJ2 can handle up to 0.5 kW at a 20% duty cycle per hour.
2. Stroke Height: Measure the vertical distance that the screw jack needs to overcome.
3. Accuracy: Determine how precise the positioning of the load needs to be. You can read more about accuracy here.
4. Lifespan of Ball Screws: Unlike trapezoidal threads, ball screws can theoretically be designed for a specific lifespan. Use the manufacturer's dynamic load rating, along with the axial force and screw speed.
5. Self-Locking: Since screw jacks are often used in safety-critical applications, self-locking is an important feature. The degree of self-locking depends on the screw pitch. If the pitch angle is greater than 4.5°, there is no self-locking. Between 2.4° and 4.5°, you achieve static self-locking (i.e., no movement from rest), and under 2.4°, you achieve dynamic self-locking (the system self-brakes).
6. Buckling Force: Depending on the screw length, mounting conditions, and axial force, the screw may buckle. Particularly long screws are more susceptible to such failure. Buckling safety should be between 3-6. Buckling tests are conducted according to Euler or Tetmajer. Check out these calculations here.

3. Third Step: Calculate the required torque and speed

Now, you need to calculate the speed at which the load needs to be moved. Is a fast or slow movement required? Check the critical speed for rotating screws. The permissible screw speed also depends on the length. This applies only to the traveling nut version or directly driven screws. Advice: Increasing the spindle pitch allows you to reduce the spindle speed.

It can be helpful to contact us to develop a concept together.

4. Fourth Step: Consider the environmental conditions

In this step, ensure that the selected screw jack can withstand the environmental conditions. This includes choosing materials and coatings that are resistant to corrosion, moisture, extreme temperatures, or potential exposure to dirt or chemicals.

5. Fifth Step: Consider safety factors

To avoid accidents and failures, include safety factors in your selection. This means choosing a screw jack with a higher load capacity and durability than what is actually required. With this approach, you’re already halfway there.

6. Sixth Step: Clarify design requirements

Consider how the screw jack will be mounted in your application. Some screw jacks have specific mounting points, while others are more flexible in terms of installation. Check what mounting options the screw jack offers and whether they fit your design. Also, determine if you need additional components such as brackets, adapters, or mounting plates to integrate the screw jack securely and efficiently into your design. This includes ensuring it can be easily integrated with other components like motors, sensors, or control systems, and that the necessary connection options are available.

7. Seventh Step: Consult a professional

If you are uncertain or have complex requirements, it is advisable to consult an experienced engineer or specialist. Also, get CAD data, which we can provide immediately without delay. We are happy to offer expert advice and assist you in selecting the right screw jack for your specific requirements and budget constraints.

8. Eight Step: Compare manufacturers and models

In this step, search for various manufacturers and suppliers of screw jacks and obtain quotes. Compare prices for screw jacks with the desired specifications. However, focus not only on the initial purchase price but also on potential operating and maintenance costs that may accrue over time. A seemingly more expensive screw jack might be more cost-effective in the long run if it is more reliable and requires less maintenance. For a more in-depth look at this topic, please read our article on why some purchasing decisions are based on misconceptions.

Ensure that you establish a realistic budget for purchasing the screw jack that covers all costs and additional expenses.

9. Ninth Step: Place the order

Once you have gathered all necessary information, selected the appropriate screw jack, and considered all technical and economic aspects, it's time to place the order for the chosen screw jack. Before requesting a binding offer, it is advisable to double-check that the offer covers all specified requirements, including technical data, price, delivery time, and delivery conditions.

10. Tenth Step: Test and monitor

Once you have received the screw jack, it is important to conduct regular tests and monitoring to ensure that it operates correctly and meets the requirements. Maintenance should also be carried out carefully to extend the lifespan of the screw jack.

11. Tips and tricks for speed, duty cycle, and more

To increase speed or duty cycle values, you can implement the following measures:

1. Use oil filling (Oil transfers heat more effectively).
2. Adjust the gear reduction (If performance is too high, it can be reduced, BUT this also affects speed).
3. Use ball screws (An efficiency of over 90% allows for higher speeds).
4. Increase spindle pitch (This improves efficiency and allows for higher speeds).