Load Parameters (Payloads)

Dynamic load is best illustrated by a video. Note the club head turning in the center of the Turntable. The other principle this video demostrates is that the load is not evenly distributed over the stage, because the club head is not symmetrical.

Momentary – The load that is present for an extremely brief period of time. i.e. punch press. (Measured with the center of gravity of the load being applied to the center of the carriage. Usually the carriage is not moving.)

Thrust / Lift – A force that pulls the carriage in the direction of the motor / crank or pushes the carriage in the opposite direction of of the motor / crank. Lift is the maximum thrust force required to lift or lower the payload vertically.

Lift and Thrust is best illustrated by a video. Note the club head turning in the center of the Turntable. Note the Rotary Table with the club head moving up and down on the XSlide.

Side / Horizontal – The load is not centered over the carriage and is instead offset to one side or the other of the stage, when the stage is laying flat. The center of gravity is perpendicular to the direction of travel.

Inline / Horizontal – The load is not centered over the carriage and is instead offset over the stage, when the stage is laying flat. The center of gravity is parallel to the direction of travel. The payload can be offset either toward or away from the knob or motor.

Inline / Vertical – The load may or may not be centered over the carriage, however the stage is positioned vertically, the load is traveling vertically and the center of gravity of the load is suspended outward from the carriage.

The payload in this image is on an XZ assembly. Additional parameters are involved with multiple axis assemblies. Please see the next section of Load Definitions when considering more than one axis.

Edge – The load may or may not be centered over the carriage, however the stage is positioned horizontally on its side. The load is traveling horizontally and the center of gravity of the load is suspended outward from the carriage.

This position has more affect on the load allowed on UniSlide Stages and Rotary Tables than BiSlide or XSlide Stages because of the interlocking nature of the latter assemblies.

Inverted – The stage is inverted, so that the load is suspended from the carriage. The stage is operating in the horizontal plane. (Measured with load centered on the carriage. Load can also be cantilevered and that makes the maximum allowable calculation more complex.)

Note - In certain applications it may be advantageous to place the load on the inverted stage rather than the carriage. (Seen in some XY applications where the carriage is actually affixed to another stage.) Although the stage is inverted the load technically isn't inverted because the payload is not suspended.

This position has more affect on the load allowed on UniSlide Stages, than BiSlide or XSlide Stages because of the interlocking nature of the latter assemblies.

In this instance, the 48 Series of Rotary Tables can be inverted and will carry the half load as an upright configuration. The 5990TS Rotary Table can only be inverted with a special configuration. (Contact a Velmex Application Engineering for more information.) Inverting the Turntable is not recommended.

Vertical – The stage is positioned on the Z axis (in the vertical plane). The load is lifted and/or lowered (traveling vertically). The load capacity is going to be smaller than the normal centered load.

Another factor to consider is the number of axes the system has. When looking at multiple axes, this includes the weight of any additional stages and adapter plates the base stage may be carrying, as well as the payload.

When you add additional axes whether horizontal or vertical, the load rating is generally measured at the base or bottom stage ("lowest common denominator").

When there is a vertical axis involved, the key load is the load on the vertical axis. Any additional components beyond the payload attached to that axis such as adapter plates, additional stages, etc. cannot exceed the maximum load for the vertical axis. And all the components together including the vertical stage and the payload cannot exceed the maximum load and/or the cantilever load for the base stage.

Lastly, you need also need to consider whether any of the axes or the payload creates a cantilever to the base stage.

While the maximum load a stage can handle may remain the same; the size of the payload that can be placed on the top stage would diminish because you need to allow for the weights of other devices that are part of the system.

Figure 1 - Shows the top stage - a Velmex Turntable - with the payload and a Velmex Turntable. Weight to consider here is the payload, the turntable and the plate that affixes the turntable to the next stage in the system depicted by Figure 2.

Figure 2 - Shows the second stage in the multi-axis system. This is the Y axis. Weight to consider includes the weight from Figure 1 plus the linear stage and the adapter plate that affixes the Y axis to the Z axis depicted by Figure 3.

Figure 3 - Shows the third stage in the multi-axis system. This is the Z axis. Weight to consider includes the weight from Figure 1 and 2 plus the linear stage and the adapter plate that affixes the Z axis to the X axis depicted by Figure 4.

Figure 4 - Shows the base stage in the multi-axis system. This is the X axis. Weight to consider includes the weight from Figure 1, 2 and 3 plus the linear stage. In this specific example an additional element to consider is the fact that the X axis is set on its edge making all the axes above it cantilevered.