Lead Times: What It Takes to Get Faster Castings
Our culture’s obsession with speed touches most everything and has certainly affected the 21st century industrial mindset. Some say the market is the primary driver pushing the accelerator for faster products, parts, and castings, and the urgency intensifies when a new product launch is involved. First-to-market thirst is undoubtedly a powerful motivator, especially in highly inventive and competitive industries like medical. Nevertheless, where metal castings are concerned, unless a ready-made, catalog casting can fit the application––or until such time as additive manufacturing evolves into instant casting replicators––OEMs large to small will have to press on in a creative, collaborative and continuous race with the clock.
No one would argue that manufacturing’s need for speed is a new phenomenon, but present-day Industry 4.0 technologies have tightened their processes to the point of requiring their foundry partners to keep up.
And keep up they do. OEMs and foundries may look at expediting casting lead times from different lookout towers, but they chiefly agree on the most effective solutions. Both factory and foundry stand to gain cost advantages by producing with greater efficiencies, which results in shortened lead times. Both also have strategic roles to play, individually and then collectively as partners with a shared objective.
Of course, everyone with engineering experience understands, too much hurry can backfire. Bob Mueller, senior SQE and resident castings expert at Komatsu in Milwaukee, cautions that when speed usurps part quality on the priority chart, it’s a lose-lose proposition.
“When we look at expediting, we have to always be aware and constantly re-emphasize the fact that nothing should sacrifice quality,” Mueller said. “It’s my experience that if you deliver a part, and you deliver it on time to some expedited date but it’s no good, we not only don’t have that part, but now the foundry is behind by one part and has to remake it or salvage it. And now it becomes very expensive––it’s costing us money, and it’s costing the supplier money and valuable time. Both quality and delivery suffer when workmanship goes to the side in order to meet a delivery date.”
Fortunately, metalcasters are employing numerous methods to skinny down lead times for their customers without compromising quality in the least. Among the more visible tools, 3D prototyping (which can melt lead times dramatically), laser scanners, and solidification modeling comprise the new standard in parts buyers’ and engineers’ expectations.
Casting solidification has long been scientifically predictable by foundry metallurgists, yet as a shaken-out casting solidifies, shrink conditions may still become evident, as do other kinds of defects, which the OEM customer relies on his casting supplier to prevent.
“And solidification models are an excellent way to do it,” said James Bohlen, senior advanced development quality supplier engineer, Ferrous and Non-Ferrous Castings at Allison Transmission in Indianapolis. “That tells [the foundry] if they need to add a filter or riser, put in a chill condition––they need to understand what they have to do before they make it. So anytime I’m talking to a potential supplier, one of my first questions is, ‘Are you going to do a solidification model?’”
Equipping the foundry to virtually “pour” a casting so the real part is done right and gets delivered quicker, modeling is used almost universally today, whether in-house or outsourced.
“They know it, they understand it and they utilize it because it’s critical,” Bohlen added. “This is where they can make the best bang for their buck as far as moving forward and making the product that is intended to be made.”
AFS Corporate Member Aarrowcast, a ductile and gray iron foundry in Shawano, Wisconsin, about 40 miles northwest of Green Bay, is a model example. President and CEO Randy Brull said following PPAP (production part approval process), solidification modeling is a major tool for expediting the overall process.
Don’t Set It Down
But beyond modeling, Aarrowcast’s biggest time-saving revolution has occurred through a strategic reduction in material handling for high-volume, high-frequency casting orders. By that Brull means they strive to avoid setting the product down or placing it on a shelf as it moves through the foundry.
“Take a core assembly for a hydraulic valve body, for example: At one time, if the core assembly had four different cores, we would make the cores, put them on a shelf, go pull them out and assemble them,” he said. “Today, we’re using just good lean concepts to produce the core and directly process and make the assembly ... Once we set that product down, there’s waste––and we’re trying to eliminate that.”
The same is true with grinding, Brull said. His company has invested heavily in robotics, but machines still share the finishing process with humans––previously, the robot would perform its work, the part would be set down, and then a man would pick it up to do his part. “Now, we’re trying to do that all in one flow,” he explained––both functions occurring in immediate sequence right at the station. “The amount of time that’s been saved by just not putting a part down or on the shelf has been significant.”
As an aside, robotics in the foundry has the added benefit of reducing error, according to Bohlen, and from his perspective, fewer problems means faster turnaround. Incorporating robotic or CNC machining to remove flash risers and gate connections allows for the OEM’s automated machining cells to accept cast parts with little to no dimensional variation.
For some mid-volume, lower-frequency jobs, Brull’s team achieves efficiencies by ganging up two or three months’ worth of orders at a time, eliminating numerous lengthy tooling changes. They might make the core and mold the parts but not process all of them through finishing––for example, where 100 pieces are required every three months, they might knock out all 100 at once but ship 30 per month according to the manufacturer’s timeline.
Another foundry technique Bohlen has observed is outsourcing various processes; in particular, purchasing high-volume core production so the foundry can specialize and focus on complex cores and not waste their machine time.
And a number of creative time-pruning efforts have become common practice at AFS Corporate Member Harmony Castings, just north of Pittsburgh. One example: The foundry will build the machining fixtures ahead of time, before they’ve even poured a casting, according to Sales and Marketing Manager Ken Foster. Sometimes they’ll also paint or powder coat first articles or a prototype ahead of time to send to the customer for approval on that portion of the finishing, which helps speed up the process on the back end.
“Another thing we do if it’s a highly cosmetic painted part, which we do a fair amount of, is send early machined first articles to the customer unpainted or unfinished so that they can start work on their side, such as their prototype builds or maybe figuring out the wiring that’s going inside the casting,” said Foster. “That could save two to three weeks of time; then, when we finally hit production, they’ll get a painted part.”
Squeezing down approval turnarounds and keeping all teams occupied simultaneously is an obvious coup for lead-time trimmers everywhere. A key consideration, and where approvals first approach the starting line, is when the foundry first receives the customer’s PO–– Brull emphasizes the importance of swiftly reviewing and confirming its content with the customer. In fact, he makes it a point to respond within hours, not days.
Squarely focused on meeting the customer’s deadlines, Foster said it’s not unusual for him or another member of the foundry team to put a casting in their car and drive it over to a subcontractor to save a day or two. In addition, Harmony’s distinctive vacuum (V-process) casting process itself offers the advantage of speed to market, said Foster. A form of permanent mold by AFS definition, V-process casting combines the benefits of traditional green sand, die cast, permanent mold and investment casting, according to Foster.
“Our tooling is soft, and it only takes two weeks to build,” he said, “So we have sample castings in three weeks on a new project.”
How Manufacturers Help Their Cause
OEM and foundry sources are a united front regarding the two most important things a manufacturer can do to contribute to the tightest possible lead time for its casting project: (1) Ensure part design can be efficiently executed as a casting, and, to reinforce that confidence, (2) Contact the foundry early in the design process and invite foundry engineers’ unique technical and metallurgic expertise.
At Komatsu’s mining group (previously P&H Mining), former metalcaster Mueller consults with the company’s engineering groups to design what he calls “castability” into parts. After a series of internal design reviews, he’ll take their solid model to one of a small group of casting suppliers and work with them to conduct solidification modeling––at this juncture, the foundry is encouraged to provide input and recommendations for additional modifications that will help remove cost and time.
“We now have a casting that meets our needs for fit, form and function, but it’s also a casting that the supplier has a high level of confidence in and can go to work on right away.”
Over time, the system Mueller put into place has achieved a high-90s percentage of right-the-first-time first articles, and he’s received positive feedback from co-workers and foundry personnel alike.
“The reality is, most of these part designs ... are already being thought of a year ahead of time, so why not use some of that time and really perfect our designs and make that good castable design right out of the gate,” said Mueller.
Not only is there engineering team buy-in for the approach, they’ve carried the castability mindset into examination of some existing complex fabrications––often concluding that the number of components, the cost, and the overall turnaround time can all be decreased by converting to a casting.
Bohlen at Allison Transmission serves in a similar casting-consultative role and likewise underscores the importance of creating a part design that’s going to be doable. CAD- and casting-experienced engineers are dedicated to making the most of their designs, in one case incorporating 18 cores on the subassembly and several internal core passages, said Bohlen. Knowledgeable upfront engineering coupled with foundry input to verify castability made the project a success.
“It was quite an accomplishment,” Bohlen said. “I believe they made five transmissions without any failures at all on the first go around; one whole transmission weighs 7,000 lbs.”
When a shorter lead time is of high importance, manufacturers are well advised to fully understand the specific capabilities and niches of their foundry partners. Do this by carefully qualifying metalcasters and developing a solid but small inner circle of trusted suppliers for each type of casting required for the OEM’s products. Where there’s established relationship with a qualified foundry, casting deliveries are more likely to meet or beat the deadline.
“Marry up with your suppliers to understand what they do well and what they don’t do well, and put product where it fits their niche, said Mueller at Komatsu. “Once you go outside that niche, you’re doing nothing but creating problems for your suppliers and delaying delivery of good quality parts. (A tangential word to the wise: When price-motivated buyers take a machine gun approach to RFQs, spraying specifications out to countless foundries from a list, it’s a surefire way to alienate high-quality foundries––sources say it doesn’t happen too frequently any more, but if it does, they generally pass on mass-blasts for quoting.)
U.S. foundries of all types would like to see greater levels of collaborative exchange with their manufacturing customers, especially at the earliest stages of part design. Why? Because even an experienced parts design engineer could overlook a casting nuance that might add unnecessary or unforeseen complications and heap extra effort and time onto a project.
“There are always opportunities where we’d like to work with the customers to engineer out some of the foundry challenges and make what I call a more foundry-friendly casting,” Brull said, “which saves us time and energy and cost.
“Once we get in early and work with them to make those design changes, we can do a much better job making the most efficient casting possible,” he added. “And if we can make an efficient, low-scrap casting, our lead time is going to be reduced. If we can tweak a design to possibly eliminate a core or eliminate a core assembly, that’s going to reduce our processing time in the foundry.”
Another good reason to get in touch early with the selected casting source is potentially limited capacity at the foundry. On one front, labor capacity is an ongoing factor, according to Brull. He says the more visibility parts buyers provide on casting orders, the better he can react and hire more people for upticks in business. The second front is the more insidious risk of foundries maxing out on production capacity as business conditions resume normalcy and manufacturing gains full steam.
“Once we come back into full circle, I think there’s going to be limitations on foundries’ capacity in the United States, with regards to what the U.S. manufacturing base is asking for,” Bohlen contended. “And as we’ve lost foundries that gets worse. If you foresee in the next couple of years that you’re going to put a constraint on a foundry’s capacity, you better start knocking on their door now; otherwise, they may not be able to fit you in their schedule in the near future.
“Metalcasting capacity in the United States is going to start hurting again as we ramp up to higher productivity,” he added.
Can’t We Just Talk?
Foundries frequently don’t see a part design until it’s knocking on the door for a quote. So, what are the barriers to proactive collaboration? Like the science of casting, it’s complicated.
Every manufacturer operates with varying protocols, processes and organizational structuring, which can determine how personnel interact with the company’s casting suppliers. In one true scenario, an OEM assigns either a machining house or a foundry to be the “Tier 1” responsible for the completed component, depending on how the OEM’s commodity manager weighs a job’s priorities and specifications. So when a machining house acts as the foundry’s customer, essentially a middleman between the OEM and the foundry, early design discussions and time-saving interventions are virtually protocolled out of existence.
Or perhaps parts engineers are not accustomed to external collaboration and view their designs and the foundry the way an architect might execute her blueprints with a contractor: Just build it. In addition, Foster at Harmony Castings suggested that COVID-19 mandates to work at home inserted further layers of complication to inhibit dialog.
Elsewhere, the purchasing department or “buyer” might be a gatekeeper of sorts, unwittingly or by design, serving as a nontechnical liaison with the foundry rather than connecting factory and foundry engineers for direct communication. Finally, even where good technical communication is the norm, people and projects can occasionally fall behind, and engaging with foundry engineers falls off the radar till the job’s on fire.
Whatever the circumstances happen to be as a new casting design takes shape, two practices should remain top of mind: Foundries should never stop seeking and exploiting innovative solutions to reduce lead times; and parts buyers and designers should talk to foundry experts as early as possible in the planning process. CS