Design Communication II
|MEC 1012 Assignments|
MEC 1012 - Assignment 5
Tolerancing for Process Capability and Fit, and Revision Control
Due in lab week 9
Produce a full set of working drawings for your functional mechanical assembly from Assignment 4. Write a manufacturing plan. Release your first version of the design, revise the design, and then release the revisions.
Checklist: (hit links for details)
- Process Capability - Expected variation in size when only random variation is present. In plain english that's how much you can expect dimensions to vary from part to part when the process is done properly.
- Tolerance - Allowable variation is size. Tolerances should be less than expected variation.
- Clearance Fit - Parts always clear (even in the tightest case).
- Interference Fit - Parts always interfere (even in the loosest case) where a 'line to line' (same size/location) fit counts as interference.
- Design Release - Exposing your design to the world outside the design team.
- Working Drawings
- Assembly Drawing
- Parts List - Following this theme of creating and maintaining consistency you now will want to modify the PARTS LIST standard to use FILENAME as a column in place of the PART NUMBER default.To do this, in the drawing mode, go to Format/Standards/Parts List/Column Chooser/Remove description and part number and add filename.Insert the modified parts list.
- Explosion with Correct Trails - Please pay close attention to your trails.
- Weldment Drawing
- Weld Notes
- Parts List - as above
- Part Drawings
- Fully Dimensioned
- All Tolerances Consistent with Minimum TolerancesMinimum Tolerances (for this assignment)
+/- 0.10 mm
+/- 0.05 mm
+/- 0.03 mm
+/- 0.10 mm
+/- 0.02 mm (diameter only)
A real matrix of process capabilities would be much more specific as to process an supplier
(here's an example from ISM - Institute for Supply Management)
- Plan of Manufacturing Processes and Fit Classes - (use a common document format like .doc, .rtf or .htm and save inside your project folder - not your workgroup folder)
- How will each part be made?
- What class describes the fit between each part? (Clearance or Interference)
- Three Sets of Models and Drawings (Developing, First Release and Second Release) - Here's how to proceed:
- Your first set of Models should be developed in the normal manner with a Revision level of AX (the X indicates that revisions are ongoing).
- When you complete the first set and you are ready for your first release, copy all of your files from your workgroup folder into a new folder called 'mm/dd/yy-release' or some plain language name.
- From Windows Explorer right-click on one of the files in your First Release folder and select Design Assistant. Use Design Assistant to remove the X from your released drawings and to increment the revision level of developing drawings (in your workgroup folder) from AX to BX.
- Add a Library search path to your First Release folder and be sure to name the library after the release ('mm/dd/yy-release' or some plain language name)
- Your First Release is due half-way through lab in week 9.
- Revise your design:
- Make changes to at least 3 parts (and Assy drawing if necessary) between first and second release
- Complete revision blocks and revision tags on revised part drawings
- Release your revised drawings by copying the files (not just .idw) into a new folder (named 'mm/dd/yy-release' or some plain language name).
- Once again, use design assistant to remove the X from your released drawings and to increment the revision level of recently released developing drawings from BX to CX .
Related Links (use the Back button to return to this page)
Please send us any other good sites you find so we can add to this list:
Developed by Mary Waldo and Paul Johnson
- Process Capability from the NIST Information Technology Laboratory
- Process Capability at isixsigma.com
- Process Capability Analysis For Production Tolerance Assignment
- Engineers Edge Handbook (You will LOVE this link)
- Autodesk Tutorial on Managing Properties with Design Assistant
- Op-Ed by Thomas Friedman on outsourcing and innovation