Questions Group IV.docx

Questions and Answers Round 4.

1. There are newer Controllers and Drives available that would perform better than the outdated Parker 6K Controller and Gemini Drive Amplifiers.

Answer:

Please use the part numbers listed for required controllers and drives.

2. The items below that are not filled in are a function of the load capacity of the linear motion and the motor(s) and the line voltage used. There really is not enough specification to adequately address these.

Axis Load Max. accel Max decel Max speed Average speed Repeatability Settling time Allowed

X 5 m/s Less than 5 m/s + 25 microns

Y 5 m/s Less than 5 m/s + 0.1 mm

Answer:

Please check the latest PSD document - The rails and motors (or equivalent) have been specified now.

3. There is no mention of a need for a brake on the vertical axis where this is usually required.

Yes, a brake will be required on the vertical axis.

4. The request for the mounting of all motors to be at the 12 O’clock orientation somewhat limits the ability to use a high speed actuator for the vertical axis. Most of the higher speed mechanics are either belt drive or rack and pinion and require a right angle mounting. It appears in the drawing that there is a 400 series Parker Screw Drive Actuator as the vertical axis, this is only rated for about 1.2 m/s.

Answer:

Please come up with own design to meet requirements. The drawings are for informational purposes only. Check the latest PSD. The rails and motors (or equivalent) have been specified now.

5. “The three vertical stanchions of the gantry system shall be connected to two sets of parallel horizontal rails. Each set of horizontal rails shall consist of two identical rails which shall be connected to an outside stanchion and to the central stanchion. This shall give the appearance of two parallel, single horizontal rails, with connections to all three stanchions….”

Answer:

Please check the latest PSD. Paragraph has been reworded.

6. During presolicitation, I inquired as to whether or not there was an incumbent for this project and was told there is not. However, today’s amendment leads me to believe that this is a COTS item for an existing producer.

Answer:

There is no incumbent for this project and there is not a COTS solution. A gantry serving similar purposes does exist but it is different in terms of its size. It is not located here at Hill AFB. We anticipate that every contractor that looks at this will be required to perform engineering work to create their final design.

7. On the technical side, it seems the spec changed the resolution to a much tighter number around 1 to 2 microns for stopping resolution in the questions and answers which came out early last week. This resolution is now smaller than a fog particle and last week it was 1/4 of a strand of hair. Based upon temperature variants of +/- 7 deg F and the changes in steel size over this 14 degree range the stopping resolution is not technically possible.

Can you please help us to understand these specs?

Answer:

On the vertical axis, our latest version of the spec calls for repeatability of +/- .1 millimeters. We have product literature that shows that repeatability of +/- .05 millimeters can be achieved. On the horizontal axis, our latest version of the spec calls for repeatability of +/- 25 microns. We have product literature that shows that +/- 1.3 microns can be achieved.

If you have received conflicting information concerning the repeatability, the vertical repeatability from the purchase spec of +/- .1 millimeters will take precedence, and the horizontal repeatability requirement from the spec of +/- 25 microns will take precedence.

8. The spec calls out The HLE-Z linear drive system for the horizontal axis can achieve 5 m/s velocity, however the vertical ball screw linear drive max is 3m/s. Does the existing system achieve these velocities in X and Z or in X only?

Answer:

The vertical axis calls for the Parker 406XR (or equivalent). Please follow the specifications from the PSD.

9. There is a list of several software deliverables but the actual functional requirements are not listed making the logic estimation difficult. Is there a functional software spec or would Hill AFB provide the software from the current systems?

The contractor will not be expected to interface with any Air Force developed software. The contractor should develop its own test routines to demonstrate gantry functionality.