3D printing, or Additive Manufacturing (AM) has become one of this decade’s hottest subjects. Nevertheless, many situations in which 3D printing may boost innovation and production, while simultaneously decreasing cost and time to market, are commonly overlooked. AM is one of the most effective prototyping methods for design optimization, however the process also lends itself wonderfully to less-likely considered applications which include the printing of jigs and fixtures, useable injection mold cavities, casting patterns, and durable end-use parts. Whether your application calls for the smooth finish and ultra-high resolution of PolyJet, or the strength and durability of Fused Deposition Modeling (FDM), here are the top 5 things you should be doing with your 3D printer.
The most recognized field for AM is easily rapid prototyping. Nearly every product can benefit from a cost-effective prototyping solution to help optimize the design, and make it production-ready.
Traditionally prototypes were either made of wood, metal in woodwork, or through custom machining. Let’s focus on the third option, as it pertains to most situations today.
Custom machined prototypes are generally functional and aesthetically pleasing for clients and product managers, however the cost and lead time of employing this method for prototyping are highly dependent on both part geometry and backlog of orders that a shop may have.
“By the time a conventional prototype can be made, it’s possible to invest large amounts of time and money in a design that doesn’t work.”
-Bruce Vanisacker, Dana Corporation
At Dana Corporation, a Tier One automotive supplier and component designer, conventional prototyping via either custom machined part or custom mold often took weeks or months to complete, and cost the company tens of thousands of dollars. “By the time a conventional prototype can be made, it’s possible to invest large amounts of time and money in a design that doesn’t work,” says Bruce Vanisacker, designer for Dana’s Rapid Prototyping/CAE Services.
Upon evaluating multiple 3D printing systems, Dana Corp found that FDM technology available on the Stratasys Fortus 3D printer provided the highly accurate and durable parts they required for both visualization and functional testing. The clutch assembly below was printed on the Fortus, and showed Dana Corp right away that the design concept would not meet the application. This spearheaded their design modifications to meet the customer’s requirements at a very early stage, and saved the company from wasting additional time and money on the concept.
Dana Corporation clutch assembly prototype built in multiple colors of FDM material
Although an manufacturer may have the capability to machine prototypes in-house, the opportunity cost generally involves removing at least one piece of equipment and a skilled machinist from the production line. With AM, a single part, or better yet, multiple revisions of a single part may be printed at once, and a skilled machinist does not have to devote their valuable time to supervise the process. The shop can now dedicate all resources to moving end-use parts out the door.
Skipping the prototyping stage of product development is a common practice when a strict deadline or budget may have to be meet. Prototyping is also commonly one of the first items slashed during a budget cut or recession. In the game of getting everything 100% correct on the first try, the odds are stacked substantially against design engineers. Discovering a mistake during production may result in costs an order of magnitude above what would have been wisely spent on a prototype. The secondary effects of delayed time to market may be even greater.
Whether functional testing of a design (or multiple versions of a design), or supplying an aesthetically striking prototype to management or an investor, AM makes the process faster and cheaper.
JIGS AND FIXTURES
Jigs and fixtures are employed throughout the manufacturing industry to reduce both cost and cycle time, while concurrently ensuring accurate and repeatable part production. Despite the crucial role they play in manufacturing and quality control, jig and fixture fabrication is an often-overlooked field for AM, with a huge potential for financial return.
By using AM, production of a custom tool no longer ties up valuable resources on the manufacturing floor. The tool can be prepared in CAD software, built on the printer, and post processed with little technical expertise or direct labor. Complex tools with custom contours or difficult-to-manufacture features take no longer to produce than simple tools of the same size.
Oreck Manufacturing Company uses its two Fortus printers to produce hundreds of custom inspection fixtures for its Coordinate Measuring Machine (CMM). Before using AM, the QA department had to wait on 20 to 30 sample parts for first article inspection to arrive from the production floor before beginning to build custom fixtures and writing the CMM programs…a process that required an additional 30 days once the parts showed up!
Using AM fixtures, Oreck completes CMM programming before first article parts arrive
Now Oreck employs two Fortus FDM machines to build part replicas and their accompanying custom fixtures which are then used to create the CMM inspection programs as soon as tooling orders are released. This ensures QC is ready and waiting when first articles arrive from Production. “I can now inspect all of the first articles for a new product in one day, as opposed to one month in the past,” said Craig Ulmer, senior quality assurance lab technician. A 29 day decreased time to market for a common $250 appliance can be conservatively estimated to increase profit by over $100,000 for the company.
Oreck also uses AM for pallet assembly fixtures, engineering test fixtures, CNC milling fixtures, and even complete product mock-ups.
Lowering the threshold of justifying a new tool means departments often find themselves printing jigs or fixtures for tasks they never even considered practical before the purchase of their machine. Every small process that could be simplified and expedited with custom tooling has the potential for return. Let’s do the math: if a custom fixture decreases a 30 second operation by merely 5 seconds, within a 10 hour production day and a shop rate of $100 per hour, we are looking at a potential savings of around $165 a day. With a 5-day work week, this could result in an annual savings of $43,000, and justify the entire cost of owning the printer!
FDM tooling has another advantage in automated tooling, where a robot arm collision likely means costly repairs and long machinery downtime. Thogus Products, an injection molding shop, uses FDM robotic attachments to absorb the impact and isolate the arm from damage in the event the tool crashes into an obstacle. Even if the tool is broken, a new one can simply be printed from a digital file stored in a database versus ordering a new one or pulling a spare from an inventory that takes up valuable shop floor space.
Injection Molding (IM) involves injecting heated plastic material into a mold, where it hardens and conforms to the shape of the cavity. IM can produce highly accurate, and highly complex 3D end-use components made of thermoplastic or thermoset materials. The process lends itself extremely well to mass production, as the molds have an extremely long service life, and each injected part is very inexpensive to manufacture
“By 3D printing the injection molds with Digital ABS, we’re able to achieve the high quality associated with traditional manufactured prototypes,”
– Stefano Cademartiri, Unilever
Tool steel injection molds can last for millions of cycles, however they can take months to complete and commonly reach from the tens- to the hundreds of thousands of dollars. Soft tooling, or molds made of aluminum, can be used if a mold life in the tens of thousands of cycles is sufficient. These are much less costly (commonly $2,500 – $25,000) and normally take 2 – 6 weeks to produce.
The development of an injection mold has the potential to compound these costs and lead times, as the IM must be completed before a prototype can be made. If an issue in not discovered until this stage, be it either a geometry interference, improper part shrink compensation, etc, additional time and money must be invested to either fix the mold cavity, or produce an entirely new one from scratch.
PolyJet is an AM technology exclusive to Stratasys, and produces smooth, accurate, and highly detailed parts. Digital ABS material available on the Connex line of printers can withstand the temperatures required for IM from 10 to 100 cycles, making it perfect for prototyping or even extremely short-run production parts. Manufacturers can put the printed mold directly into IM equipment, and produce prototypes of the same material used for production parts.
A 3D printed injection mold of a toilet rim block manufactured by Unilever
For this reason, Unilever’s Italian facility invested in a Stratasys Connex500 3D printer to print prototype injection molds, blow molds, and thermoform molds for accelerated part development without the need for conventional tooling. “By 3D printing the injection molds with Digital ABS, we’re able to achieve the high quality associated with traditional manufactured prototypes, while ensuring that the high temperatures and pressures of the injection molding process can be sustained,” says Stefano Cademartiri, R&D, CAP and prototyping specialist at Unilever.
Unilever reports that their Connex500 delivers prototype iterations 50% faster and at, on average, 20% the cost of traditional molds. This results in a 40% faster development time.
During the designing phase, PolyJet molds offer a clear advantage over traditional methods. A 3D printed mold is much cheaper than conventional tooling, and more importantly, much faster to manufacture. Features that are difficult to machine and drive mold prices up make no difference to cost or production time with AM. Design iterations can easily be printed and used within a day or two, driving product innovation and speeding up time to market.
PATTERNS FOR CASTING
Sand casting is a manufacturing process where a pattern in pressed into sand mixture to create a cavity. The cavity is then filled with molten metal. This process is very efficient for low- and high-volume production. Automated processes can make high-volume sand casting very fast and economical.
The most common method to produce patterns is through CNC machining. If shrink compensation is incorrect, or design flaws are identified, a new pattern must be manufactured. Furthermore, the intricate gate and runner system of the mold is generally cut and hand-sanded from a material such as Ren board, as refinements may be required for the final design. Both of these situations result in longer lead times, additional manual labor, and higher cost.
By 3D printing these components, sand casting can benefit from pattern cost and lead time reduction, faster design revisions and pattern optimization for casting, and interchangeable gate and runner systems.
AM is an ideal solution for sand casting when any of the following conditions apply:
- Molds are intended for prototyping or low-volume production
- Casting designs need verification
- Gate and runner refinements are likely
- Castings will be complex or large
Melron Corporation, a manufacturer of window and door hardware, traditionally hired subcontractors to CNC machine 18″ x 13″ aluminum matchplates for around $5,000 apiece. Each plate took 3 – 4 weeks to receive, leading Melron to order an FDM part from a service bureau. The cost and times savings of using the printed part versus conventional tooling can be seen here:
The printed part worked so well that the company ordered its own Stratasys FDM machine, and began printing parts in-house. “FDM is facilitating our transition to new markets by enabling us to produce matchplates at a lower cost and in less time than ever before,” said Dan Schaupp, engineer for Melron Corporation.
Investment, or “Lost Wax” casting is a process where, traditionally, a sculpted master pattern is used to cast an IM. This mold is used to produce multiple patterns made of wax or another other compatible material. Each wax pattern is covered in a ceramic slurry which hardens around the pattern. The wax is then melted out in a furnace, leaving an empty cavity in the ceramic mold. Molten metal is poured into the mold and left to cool, after which the ceramic mold is broken away, leaving a cast part.
Investment casting generally produces parts of much higher accuracy (0.005 inch or 0.127mm is common) and surface finish than other casting methods, and is typically used applications with relatively low production quantities and changing product design.
Today the master pattern has been widely replaced by a machined IM, subjecting it to the same limitations discussed earlier. Due to the high cost and lengthy lead time to produce an IM, a secondary effect is felt by the investment casting foundry.
Typically the foundry cannot produce a prototype ceramic mold until the IM is complete and a pattern produced. If problems with the prototype pattern are discovered at this stage, the repair time further delays the investment casting process.
The FDM prototype may act as a direct replacement for the wax pattern
Using AM, a prototype of the master pattern can be produced very quickly to verify pert geometry and identify any problem areas that may occur. Once the foundry is sure the part is correct, they can being the injection mold manufacturing process with much more confidence.
Due to its ability to burn out of the cavity, FDM prototypes can be prepared for casting with simple post-processing techniques, and may act as a direct replacement to the wax pattern. Because the ceramic mold is sacrificial, and broken away from the cooled part, a 3D printed prototype can be used that contains draft angles, undercuts, and other features ordinarily limited by the IM process.
PolyJet technology may also be implemented to streamline the investment casting process. In addition to building the pattern, a low-production or prototype injection mold may be printed to create wax patterns for casting. By using AM in this application, the casting foundry could see the same benefits discussed during the IM section earlier in this paper.
END USE PARTS
One of the more common misconceptions of 3D printing is that it will become an alternative to mass production. Why go through the process to machine or cast a part when you have the option to print it?
While the initial investment of, say, an IM tool is very high, the cost of each molded part is extremely low. Conversely, the per-part cost of 3D printing is relatively high, and may result in a far greater expense over the production of thousands of parts. Additionally, IM may turn out 6 parts a minute, whereas AM my take several hours to build a tray of parts.
Areas where AM excels in end-use parts, or what is known as Direct Digital Manufacturing (DDM), are short-run part production applications, components with complex geometries, custom manufacturing, and, much like prototyping, frequent design iteration.
Part geometry is a crucial factor with traditional manufacturing methods : the more complex the design, the more time and skill it requires to create, and the higher the price. What may look to be a simple feature in CAD may be a nightmare to fabricate. The beauty of AM is that it is much less restricted by geometry. Because the printer deposits the material layer-by-layer, there are no geometry interference or tooling limitations to contend with. Professional printers offered by Stratasys use soluble support material as well, meaning complex internal cavities may be printed and then hollowed out entirely hands-free.
“Today, all our MINIs are racing with FDM wheel arches,”
-Paul Doe, Prodrive
The Aerospace industry’s low-volume production make DDM an attractive, low-cost alternative to CNC machining and complex tooling. Society has always looked to Aerospace for the early adoption of disruptive innovations and future technologies. 3D printing has helped shape the industry for over 20 years, and with Stratasys’ introduction of ULTEM 9085 to its extensive line of materials, DDM has seen widespread implementation across the Aerospace industry.
Aircraft structures can now quickly be made stronger, lighter, more complex, and yet at lower cost. Boeing uses 3D printing to design custom interior configurations when building aircraft for multiple airlines. The same basic plane may be outfitted with different air ducts, panel covers, grates, clips, brackets, and a myriad of other interior components to suit the customer’s needs. When only a handful of these parts will ever be manufactured, the cost of building custom tooling is very expensive and time consuming. Additionally, AM has made it possible for components that once had to be manufactured as intricate assemblies to now be printed as single parts.
The motorsports industry has begun adopting DDM to produce race-ready custom parts. UK-based Prodrive is one of the largest and most successful motor technology businesses in the world, and currently uses up to 15 FDM parts on their FIA World Rally Championship (WRC) series MINI John Cooper race cars. “We make only 25 cars per year, so it is hard to justify tooling costs. FDM eliminates tooling, which keeps cost down and shortens response time,” says Prodrive’s Chief Designer, Paul Doe.
Prodrive uses up to 15 FDM parts on their WRC MINI John Cooper race cars
AM has been crucial in their design assessment and testing, and now Prodrive’s FDM machine builds production parts that include gauge pods, wheel arches, and an aerodynamically optimized hood vent whose shape would prove extremely difficult for molding or carbon fiber lay-up.
A last minute styling design change to the vent was actually made possible through the use of AM, as the manufacture of new tooling was not required. In another example, upon inspection of the car, FIA took issue with the aerodynamic configuration of the rear wheel area. New rear wheel arches were conceived and manufactured within 24 hours. “Today, all our MINIs are racing with FDM wheel arches,” says Doe. Despite the heavy toll racing takes on the arches, “During rallies, our only failure has been the bond [between the part and] the car.”
A final note on DDM is that production is also extremely scaleable with AM. If you have a number of machines running on the manufacturing floor and suddenly need to double your output, you can add machines quickly to ramp up production without the associated time and cost of shipping heavy machinery, or seeking out and training additional specialized machinists.
Disruptive technologies will continue to drive innovation and market adaptation. As an increasing number of industries evolve to incorporating 3D printers into prototyping, jig and fixture fabrication, injection molding, casting, and end use part production processes, many companies will begin to realize they cannot afford to remain stagnant with outdated tactics.
Take a look at your company’s current design and manufacturing processes. Even if these five specific applications do not fall in line with your occupation, chances are you may find a few that could be streamlined through the use of AM.
ABOUT THE AUTHOR:
Kenny Hart completed his bachelor’s degree in Mechanical Engineering at the University of Central Florida, and is currently an applications and consulting engineer for NeoMetrix Technologies, Inc. At NeoMetrix, he specializes in exploring applications for 3d printing, as well as in the use of multiple optical metrology and 3D scanning technologies for reverse engineering and inspection. Kenny has extensive experience in the application of this technology in a variety of industries, including aerospace, automotive, consumer products and medical fields.
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