Shop Solutions Continued from page 44
through the bottom. Some designs call for heat treating, use of bronze bore liners, or bronze plating on the bottom of the part, its running face. Liners may be cast in or produced on Waltz’s screw machines, then anchored into retaining grooves with a ballizing process or swaging.
“Nine bores are common to most all pump designs. We must maintain tolerances of 0.000020" [0.5 µm] for bore roundness, 0.000040" [1 µm] straightness, 4–8 µin. [0.1– 0.25 µm] Ra
bore finish, and less than 3 µin. [0.07 µm] sur-
face on the pistons. We have three Zeiss CMMs that can scan the piston bores at various levels for cylindricity, too. All these parts are serialized, traceable to the material and processes used to create them,” said Waltz.
“During prototyping, we determine where to leave needed stock on the part, but we fine-tune the stock allowance over time and tweak our processes to be as efficient as possible. For example, heat-treated parts are often carburized which creates only a thin layer of surface hardness at about Rc
54. Thus, we want to remove as much metal as possible before
hardening, so we aim for 0.0010 to 0.0015" [0.0254–0.0381- mm] honing stock in the bore in the hardened state. Parts with bronze bore liners are, of course, a different story.” Waltz had been using standard horizontal honing technol- ogy from Sunnen, where outcomes are heavily dependent on the operator’s skill. The operator would hone one bore, clean the part, air gage it at three different levels and then at 90° bottom/middle/top to see if there’s any issue, such as taper at the bottom of the bore which would have to be feathered out.
Sunnen’s multifeed control technology on the SV-1015 allows the user to select the better tool feed option—rate feeding or force feeding—to suit the workpiece geometry, material, and tool type/size.
“There’s a tremendous amount of back-and-forth to com- plete nine bores, and if you blow one bore, you’ve scrapped a part valued at several hundred dollars. After honing, we must have confirming CMM inspections on each part, each bore, and this becomes part of the manufacturing history for each block. Honing and inspection could easily take two hours per part,” said Waltz.
“Our challenge to Sunnen was to automate everything, in- cluding part indexing, air gaging, and recording of gage readings for the part’s history. We achieved all this with the new Sunnen SV-1015, but it was one of the new patented standard features in this machine—multifeed honing—that has played a role in taking our honing process capability to a new level,” said Waltz. The new patented multifeed honing capability gives users a choice of tool-feed modes to achieve the shortest cycle times, lowest part cost, and longest abrasive life. Multifeed combines
66
ManufacturingEngineeringMedia.com | December 2013
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84