Consider these 5 key points before purchasing a precision lift table for your integration project.
1. Tolerance :
Determine the amount of deflection that is acceptable for your application. Precision lift tables can have repeatability in elevation that is as good as +/- .025 "of an inch.
2. Allowable Load Drift:
If your application requires zero load drift, then you a precision ball screw lift table might be your best option. These Electro-mechanical lifts are powered by an electric motor which turns a screw which in turn raises and lowers the lift. They are very precise and also have zero load drift. This unit is great for applications that need to have stability at any height and for prolonged periods of time.
3. Loading Conditions:
It will be important to know how the load is transferred onto and off of the precision lift table. If your application requires the lift to be loaded at a mid-stroke position, (that is where the lift is not fully raised, or fully lowered) then you need to have clear with the manufacturer on how load is placed onto the lift. For instance, if the load is rolled onto the lift, this could present major offset loading problems for the precision lift table. If the load is lowered onto the lift, then there is less of a chance for deflection and damage to the lift.
4. Controls :
The method in how the precision lift will be controlled has to be discussed early in your planning stages. Most automated lifts are controlled with a PLC rather than a human operator, However, if an operator is responsible for cycling the lift, then the unit will likely have to be equipped with a vertical string encoder or limit switches. The vertical string encoder will keep the PLC informed on what elevation the lift is currently at. This allows it to stop at predetermined heights as required by the application. The limit switches work in much the same way, but with less flexibility.
5. Duty Cycle :
Precision lift tables are often high duty cycle lift tables as most automation does not involve the human operator. Thus, the lifter must perform its cycling at an accelerated rate as its output is much higher than a traditional lift. Duty cycling can be as high as 120 times an hour based on the application requirements and the material that is being produced. If this is indicative of your application, then this will require the precision lift table to be reinforced at the scissor joints, the scissor tracks, and also the roller wheels.
Source by Scott Fullerton