“It is a matter of creating a shape that would be diffi cult to completely fabri- cate. It’s thick-walled, you have areas that support a lot of load, and you would have welds taking on that load.” Manitowoc Cranes buys both in-
vestment and sand castings, and while 100% of the components are steel, the alloy specifi cations can vary greatly among parts. For example, the cranes’ structural boom joints, two of which are situated at every intersection of boom segments, must not only be strong and lightweight, but also weld- able so that it can be affi xed to the upright structures. In addition to the parts it sources that
go directly onto its crane assemblies, Manitowoc Cranes purchases castings in at least two other ways. First, the company purchases a number of cast- ings that end up in welded assemblies it constructs in-house. Second, it is intimately involved in an even more indirect manner of purchasing cast- ings—those that are included in the fully assembled pieces of equipment that ar- rive at its doorstep, such as gearboxes. “Indirect casting purchases are as im-
portant as direct purchases,” Reybrock said. “[For some assemblies], we are indirectly involved in the managing of the value propositions. We would not have direct contact with the metalcaster, but we want to understand the makeup and complexity of the assembly.”
The Sourcing Strategy One of the central tenants of Mani-
Manitowoc Crane buys more crawler pad track shoes than any other casting.
up the crawler bases. What’s more, many of the shoes are interchangeable and can be used on multiple platforms. The vol- ume of the parts used on each machine make the track shoes ideal for production via metalcasting. “We look at volumes fi rst, shapes second,” Zick said. Indeed, many of the parts Mani-
towoc Cranes produces as steel fab- rications have the look and features of components that would generally
Online Resource
Visit
www.metalcastingdesign.com for an audiocast with members of Manitowoc Crane’s design and purchasing team.
be associated with castings. Scattered around the sprawling Manitowoc manufacturing campus are parts with intricate geometries, multiple changes in section thickness and several weld- sites that could be eliminated with metalcasting. But if only a few of the parts will be used in a calendar year, the idea of casting them is shelved. Zick said exceptions to this rule
exist. The tumbler teeth used to drive the company’s cranes up and down their crawler pads are just such an exception (Fig. 1). While only a few of the parts are used on each crane, their geometry makes them ideal for metalcasting production. “It’s a pretty unique part,” Zick said.
24 METAL CASTING DESIGN AND PURCHASING
towoc Cranes’ casting sourcing strategy is a fortunate one for a company look- ing to replace lost metalcasting exper- tise—concurrent engineering. “We practice integrated product
development with all of our casting suppliers,” Reybrock said. While Manitowoc Cranes is seeking to
grow its in-house casting expertise, it will continue to rely on its metalcasting sup- pliers to provide much of the guidance it needs, and it will continue to rely on it early and often, according to Reybrock. “It’s as much about the suppliers as
us,” he said. “We’re the experts relative to cranes, but the casting guys are the experts in casting, so it’s the early col- laboration that makes us successful.” Of course, Manitowoc Cranes won’t
leave the existence of that casting knowl- edge up to chance. The company has certain safeguards in place to make sure each of its casting suppliers are indeed
SEPTEMBER/OCTOBER 2010
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