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Speeding Up Moldmaking Processes

 

With more reshoring of moldmaking, manufacturers turn to faster processes to boost moldmaking productivity

  

Patrick Waurzyniak
Senior Editor

Moldmaking is making a comeback, with more reshoring to North America of mold-and-die manufacturing that left for the Far East and other low-cost manufacturing centers. With faster metalcutting through high-speed machining (HSM) and improved EDM techniques, mold-and-die shops are finding innovative ways to compete with manufacturing operations in traditionally low-cost labor markets.

More HSM on newer five-axis machines has changed the equation for moldmakers, who increasingly see greater savings through better mold turnaround times and cutting shipping costs by bringing moldmaking back to North America. With high-speed milling of molds on fast five-axis machines running between 42,000–60,000-rpm spindle speeds, today’s moldmakers can achieve very high tolerances, enabling machinists to achieve nearly mirror-like finishes on molds and dies, noted Gisbert Ledvon, director of business development, GF Machining Solutions (Lincolnshire, IL), a builder of both high-speed milling machine tools and EDM machinery.

 

Fast Milling Speeds MoldmakingG.H. Tool & Mold was able to transition many of its smaller intricate parts, such as this valve body mold component at 46 Rc hardness, from older five-axis machines to its Mikron HPM 800U-HD that not

“More and more moldmakers are now utilizing five-axis high-speed milling for their mold work. They’re finishing a lot of parts even in the hardened stage without using EDM, or they try to avoid EDM where they can because it’s a longer process where you have to make electrodes,” Ledvon said.

Today’s HSM capabilities have made moving to five-axis machining more attractive to many moldmakers, he said. “They’re machining a lot with five axis now, and that was a problem a couple years back, when people were very hesitant about five-axis technology, and some of the machines didn’t really give them all of the necessary capabilities,” he added. With high spindle speeds and linear motor technology, more manufacturers are embracing this technology for milling molds.

“That really allows them to get, in some cases, almost polished finishes off these high-speed milling machines,” Ledvon said. GF Machining’s high-speed machines offer the company’s True Core spindle technology that helps operators maintain these accuracies. “There’s our new Smart Machine modules, where you have multiple sensors on the machine to compensate for any type of vibration or heat expansion, so you can hold these types of tolerances,” he added.

At G.H. Tool & Mold (Washington, MO), aluminum die-cast molds are cut to high tolerances using GF Machining Solutions’ Mikron high-speed milling machines. A design-to-order manufacturing company, G.H. Tool & Mold uses its Mikron HSM 800 milling machines for producing die-cast mold and replacement parts. Part machining cycle times vary anywhere from 30 minutes to eight hours, and tolerances typically run between ±0.0005 and 0.002″ (0.0127–0.0508 mm). Service parts for molds usually take five weeks to finish, while a complete mold is done in as little as 10 weeks.

The shop does practically all of its really critical machining on the Mikrons, according to Danny Straatmann, G.H. Tool & Mold programming manager. “They are the shop’s ‘fast movers,’” he said, for lighter smaller components and for both soft and hard machining—typically around Rc 46–48. The machines’ speed, along with accuracy and rigidity, result in far better surface finishes, and hard machining capabilities allow the shop to mill parts to finished size from hardened materials, thus reducing the amount of die-sinking electrical discharge machining time required.

 

Automation Pushes Moldmaking

Much of the reshoring of mold work has happened just in the last year or two, noted Ledvon, and a good portion of it has gone to Mexico, due to the US shortage of skilled moldmakers for the automotive industry. “It’s still a different type of moldmaking. The ones that survived the crisis are making 60, 100 and 200-cavity molds, and they have highly sophisticated, high-end moldmaking,” Ledvon added. “That’s the way they can compete. The US moldmaker has to differentiate themselves from the others, specifically the Asians, and the way to bring it back is to automate.”

 A complex multicavity mold designed in Vero Software’s VISI Mould package.

Automating moldmaking is key to improving mold machining processes, agreed Clinton Perry, product marketing manager, Delcam plc (Birmingham, UK). “Traditionally, industrial robots have been used to perform a limited range of repetitive tasks, mainly in handling materials and components. While this is now well established on large-scale production lines, we’re now at a point where robots are capable of so much more,” Perry said. “In particular, we can connect robots to a broad range of sensors, which capture information about the parts they’re working on. This data can then be fed back to the control system, and used to make decisions and adjustments to the robot’s operation, driving greater efficiencies during the process.”

A great example of where robotics can revolutionize manufacturing processes is by replacing laborious, time-intensive tasks that require a manual worker’s eye for detail, such as polishing and finishing, he added. “Human beings are naturally good at the kind of feedback loop necessary for getting a smooth surface, but we lack absolute accuracy and repeatability. Developments in software like PowerMill mean that robots can be programmed to carry out many of these tasks,” Perry said.

Recent improvements in robot accuracies have made it possible for robotics to automate many new processes. “Through its involvement with projects such as COMET [a European consortium working on a plug-and-produce platform, COmponents and METhods, for adaptive control of industrial robots], Delcam has demonstrated levels of accuracy, meaning robots now represent a serious opportunity within the industry. By combining robots with optical scanning technology, it is possible to detect blemishes and surface defects as small as 0.001″ [0.025 mm], and accurately determine how much polishing the surface needs and where it is required,” Perry said. “Thanks to the computing power and automated systems now available, the program changes can be done on the fly, based on the feedback data being collected by the robot. This approach has massive potential for improving the productivity of the robot and the quality and consistency of the parts being produced.”

Enhancements to PowerMill 2016 include the ability to automatically mirror complete projects in one operation while maintaining key machining characteristics, he added. PowerMill’s toolpath verification checks have been extended to work with complete NC programs. “This powerful feature checks for collisions and near-misses as well as highlighting movements that could cause the machine to over-travel in one or more axes,” he said. The software also now offers high-efficiency Constant Z ordering of rib-machining toolpaths to optimize the connection moves, reducing air cutting and improving overall cycle time.

 

What Moldmakers Need

It’s important to start with what moldmakers are looking for, noted Hari Sridharan, director of Application Engineering & Training (Americas)—Software Business Unit, for Cimatron Group (Novi, MI, and Givat Shmuel, Israel). “Demand is picking up, but resources are still tight, somoldmakers are looking for different ways to increase productivity,” Sridharan said. “We are seeing a trend towards hardware and software that is built specifically for moldmaking to address these specific needs—CNC machines designed for moldmaking, cutting tools that are specific for moldmaking, and of course software.”PowerMill’s automatic mirroring shown with this automotive mold saves users considerable time whenever right- and left-hand versions are needed of a part/tool or machining symmetrical objects.

From a software perspective, the big themes are automation, integration, and concurrency, he said. “Automation is critical. In the past, mold machining was considered an art,” Sridharan said. “Today it’s becoming more of a production process. Many of those working the machines today are not toolmakers by trade, which means that they need better guidance from the software. For example, allowing the designer to add machining attributes and color code the different surfaces so when the file gets to the floor the entire machining process becomes automated.”

Closer collaboration between design and NC is just the beginning, he said. “What we are seeing today is cohesive integration of the entire production process, with automated setup, in-process measurement and inspection for greater end-to-end productivity. Concurrency enables moldmakers to work simultaneously on multiple components of the job. Software companies are developing multicore, multithread and background calculations capabilities that allow programmers to run multiple jobs at the same time to expedite delivery.”

Fast, accurate moldmaking CAD/CAM software is key for users that need top design and manufacturing capabilities. With the latest TopSolid 7 software, moldmakers get a system that speeds up moldmaking design and is equally adept at the CAM side, noted Bill Genc, technical director, TopSolid USA (Addison, IL), a subsidiary of Missler Software Inc. (Evry, France).

With TopSolid 7.9 Mold, moldmakers get a package that was fully rewritten in 2009 for native 64-bit multicore processors. The software, which Missler originally developed in the late 1970s as a machine tool manufacturer, offers speed advantages for moldmakers working with very large mold files, he added. “What we’ve learned is that to have good quality CAM, you have to have good quality CAD,” Genc said.

A 300-component mold assembly can open in Top Solid in two seconds, he noted, while in other software it may take several minutes. “In our point of view, we are a manufacturing-centric software. To us, manufacturing is both design and machining,” Genc said. “TopSolid Mold software is a full manufacturing package and it’s designed to let engineers design molds ridiculously fast.”

The new Hyper-i control offers programming simplicity for Makino’s line of EDM machines.Automation in moldmaking often means focusing not just on five-axis machining, but on the 2D machining that makes up the bulk of operations, it’s as much as 60%, he noted. “A lot of our competitors have focused on the crazy five-axis stuff. Everybody forgets about 2D,” Genc said. Automated features in TopSolid let the programmer pick a method they want, and the software analyzes the features, like feature recognition, he said, only it’s much more interactive. “The system performs better than standard feature recognition,” he said. “Mold-and-die features get complicated really fast.”

With 3D machining, one of the challenges is to get a tool ready to heat-treat as fast as possible. Moldmakers are removing a lot of material, and with TopSolid’s methods tool that enables saving frequently used machining method macros. “If you’re machining a core block out of H13, the user can program it once, and then the software stores that knowledge and you can use it again. It’s a macro on steroids, with full chocolatey goodness,” Genc said. “You can add interaction to it, you can add custom dialog boxes to it—everything is drag and drop.”

The software auto-adapts itself, he added. “We’re literally taking out what’s hard to use in a CAM software out of the software.”

 

Optimizing Cutting Options

CAM companies continue to aggressively develop heavily optimized tool motion intended to standardize chip removal and cut cycle time, said Ben Mund, senior market analyst, CNC Software Inc. (Tolland, CT), developer of Mastercam software. “It’s a technique that has roots going back decades to radial chip thinning, but today’s computing power and algorithms have created an explosion in powerful new techniques. We’ve seen amazing success with our optimized Dynamic Motion technology, and we continue to apply it to more shop scenarios with every release,” Mund said.

There’s also a renewed focus on prep tools for moldmakers—CAD functions aimed squarely at assisting the programmer, Mund added. “Tools that help prep models, tools that help correctly fill in design gaps that might be left in a model, tools that create additional models that programmers might need like fixtures, electrodes, and molds—all of these are what we might call ‘CAD for CAM,’” he said. “Combined with powerful, general creation tools and tight CAD/CAM integration, these tools can be a huge timesaver for shops.”

Reshoring moldmaking has made some inroads, Mund added. “While it’s anecdotal, we’ve been seeing reshoring of moldmaking picking up for a few years. We’ve seen price increases in some areas like China drive a portion of work back to the states, as well as quality concerns coming out of other areas,” Mund said. “We’ve also seen mold work coming in from other areas that are temporarily seeing the demand outstrip supply on moldmakers, such as Mexico.”

CNC Software has expanded its Mastercam Dynamic Motion toolpaths with refined strategies for better control in specific cuts, he added. “Dynamic toolpaths are also extending into other areas such as turning [Mastercam Lathe] and will continue to expand in the future. On a related note, our new radial chip thinning feature lets you program to a tool’s specs, delivering efficient speeds and feeds while maintaining your targeted chip thickness.”

CAM requirements for toolmaking typically involve complex forms where machining is not necessarily about cycle time, noted Marc Freebrey, group marketing director, Vero Software (Cheltenham, UK). “It is how to achieve the highest possible surface quality and reduce EDM and manual finishing time,” said Freebrey.

The fundamental requirements for CAM are numerous, but the most important include automatic feature recognition of complex hole and pocket features from the CAD model. “Extraction of diameters and depths from the model makes it easy to enter drilling parameters and eliminate the possibility of manual input errors,” he said. “Intelligent toolpaths can be created for the most complex parts with toolpaths tailored towards high-speed machining and designed to minimize the number of retracts, maintain a constant tool load, minimize any sudden directional change and automatically smooth the CNC code.”A conic nose ball milling operation shown on a mold in the TopSolid 7 Mold CAD/CAM software from Missler Software Inc.

Multiaxis machining has become increasingly common and many complex molds contain deep cavity areas and small radii that need to be machined with small-diameter tools, Freebrey said.

Another big area of focus for CAM software is the finishing side, according to Shawn Schwartz, sales and service director, Americas, for Vero Software’s WorkNC CAM software brand. “Finishing is such a big deal. We’re adding a new finishing feature in the WorkNC 2016 update due out at the end of May. A major thing is the use of high-feed tooling. High-feed tooling is really the design of the tool itself, and high-speed roughing is really different.”

The high-feed tooling uses a different radius on the tip of the tool, he said, and for moldmaking it can be used to create very precise finishes that are Class A, which eliminate the need for much of the benching, or hand polishing, required on various parts or molds. “This finishing allows us to get there 10–15% faster,” Schwartz said. “That’s the largest portion of the machining in the moldmaking area.”

 

EDM for Moldmaking

Wire EDM technology also is an integral part of the tool-making process, as more molds are being designed to have fewer, but more complicated inserts that are wire-cut, Freebrey added. “Wire EDM is extremely accurate, suitable for unmanned or overnight machining, and enables the machine to cut internal corners with very small corner radii based on the wire diameter and spark gap. It becomes easy to cut square apertures without the need to split the mold or produce accurate pin holes in a plate after heat treatment.”

Many moldmaking operations involve machining smaller reinforced ribs that have features too small to effectively mill, noted Brian Pfluger, EDM product line manager, Makino Inc. (Mason, OH), and necessitate taking an EDM approach. Last year, Makino added improvements to its Hyper Technologies suite for EDM systems, which introduced a new Hyper-i control offering that significantly boosts user-friendliness and efficiency for Makino’s wire and sinker EDM machines.

The Hyper Technology line added a combination of new control features and a new generator for the EDM machines, Pfluger said. “It’s harder and harder to find expert, seasoned people, and operators gravitate toward the Hyper i,” he added. “Think of it as a giant iPad. It’s a very streamlined interface that breaks down barriers, like a smartphone or Windows technology, with a tiled user interface.”

Training is a snap with this technology, he added. “It really is easy, and probably only takes a day or two to train new operators,” Pfluger said. Pickup cycles or a tooling probe, for instance, are all pre-programmed so a novice can easily learn to use the system, which includes hyper-linked information and training tools embedded in the machine control. “When they hit cycle start, they can have confidence it’s going to do what they need to do.”

Other improvements are the sinker EDM’s faster processing with a new generator, the engine of the machine, that helps boost jump speed by roughly 10 times, Pfluger said. “It creates a hydraulic effect and flushes the debris from the cut zone,” he said. “We’re actually jumping up to 20 m and at 1.5G acceleration. It’s the 0–60 time that’s critical for EDM.”

This article was first published in the May 2016 edition of Manufacturing Engineering magazine. Read “Speeding Up Moldmaking Processes” as a PDF.


Published Date : 5/1/2016

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