Courses 41816, 41817 & 41818 - Support for Final Assignment in CAM

CASE STUDY: TORSO

The Pick-up Truck This case study will help you when you do your final assignment in CAM. This study is focused on the technique to use, when a part is problematic to clamp, like the torso in the picture to the right. Spend about 10 minutes to read this study.

The Pickup Truck is relatively easy to clamp. There are many operations to consider, but there are always a set of parallel surfaces to clamp. The torso has no parallel surfaces!

The clamping for the first operation is not a problem - you can clamp the workpiece. However, when you turn the torso to machine the back side, you have a problem.

The workshop operators in 427 favour gluing the part into a cavity for the back side milling of parts like the torso. This study will show you how this works.

Important issues:

 

 

1. THE FRONT SIDE OPERATION
OPERATION 1

The front side of the torso is no big deal. A volume milling is followed by a surface milling. All surfaces visible from the top are selected and machined.

OPERATION 1
Sequence 1 - Volume Milling - 10 mm end mill
  Parameters:
Rough_stock_allow = 0.4
Rough_option = rough_&_clean_up
Sequence 2 - Surface Milling - 12 mm ball mill
 

Parameters:
Scallop_hght = 0.02
Lace_option = Line_connect

 

Note: the surface milling sequence does not go deeper than the volume milling sequence.

2. CREATING SUPPORT PART

The front side is now finish machined. We now need to glue the machined surfaces down into a cavity, with the exact same measures.

The amount of glue to be used depends on the part. As little a possible, though the part must be held firm in place. Before glueing, the support and torso are waxed, so it is easier to take them apart after machining.

 

Notes: This is what is required: a block with a cavity to fix the torso. The exact size of this block is not critical, as long as you remember to include a slot, which is the basis for the Reference Machine Zero to be used for the back side operation.

Bottom animation:

  • Part prior to torso 'trimming'
  • After torso 'trimming'
  • To limit the contact area between the two parts, another cut is made. The glueing only has to be on the sides of the torso. It also saves time, because the surface milling area is reduced.
  • Slot for easy Reference Machine Zeroing

How to create the support part:

  • Select Mfg Model - Create
  • Choose Ref Part - name it
  • Create the part using standard Pro/e features, align it like in the top animation. The overlap between the two parts is where the glue will be
  • Open the model assembly in a new window. The Boolean operations to merge or cut bodies with one another are not available in a Mfg assembly
  • Select Edit - Component Operations - Cut Out
  • Select the part to be cut (the new support part), then the part to cut with (the torso)
  • After this you can further reduce the Support Part, like in step 3 in the bottom animation. Make the part as simple to mill as possible, while keeping its function intact.

 

3. MACHINING THE SUPPORT PART
OPERATION 2

Machining the support is straightforward. The parameters can be the same as those used for the front side. The only difference is the Pro_stock_allowance, which is slightly negative, to make room for the wax and glue. The mill digs deeper than it really should.

OPERATION 2
Sequence 1 - Volume Milling - 10 mm end mill
  Parameters:
Rough_stock_allow = 0.4
Rough_option = rough_&_clean_up
Sequence 2 - Surface Milling - 12 mm ball mill
 

Parameters:
Prof_stock_allow = -0.05/-0.1
Scallop_hght = 0.02
Lace_option = Line_connect

 


Select 'Check Surfs' to control which surfaces are used in gouge checking

Notes: In this example - in seq. 2 - I had to remove all the default 'check surfaces' Pro/E uses, to avoid unintended cutting of anything else but the surfaces selected for milling.

The cavity of a support part will always be something like in this example, so it is perfectly safe to accept all 'check surfaces' removed.

4. THE BACK SIDE OPERATION
OPERATION 3

With the torso glued into the cavity support, and the Reference Machine Zero according to the slot, the back side operation is quite simple.

Sometimes it is a good idea to go a little slower on the part , when it is glued, so it won't break loose before the milling is over.

OPERATION 3
Sequence 1 - Volume Milling - 10 mm end mill
  Parameters:
Rough_stock_allow = 0.4
Rough_option = rough_&_clean_up
Sequence 2 - Surface Milling - 12 mm ball mill
 

Parameters:
Scallop_hght = 0.02
Lace_option = Line_connect

 

 

 

End of case study