There is no disputing the value of a great product prototype. Producing your design in 3-D, testing its functionality and ensuring that the required manufacturing processes will work can save considerable time and expense. While the industry is buzzing about additive prototyping, don’t overlook the benefits of subtractive prototyping.
By Hiroshi Ono, Group Product Manager, Roland DGA Corp.
While many designers outsource their prototyping work, the industry’s most advanced technologies are bringing prototyping right to the designer’s desktop with several important benefits.
Many product designers and engineers who are researching in-house prototyping options are drawn to the hype surrounding new additive technologies, which create prototypes by fusing, binding or solidifying materials such as liquid resin or powders, layer upon layer. While bringing these systems in-house can offer significant benefits over traditional outsourcing models, for many applications, there is an alternative that can deliver a better, less expensive, better-finished prototype. This alternative is known as subtractive rapid prototyping (SRP).
Roland, for example, uses SRP technology as the foundation for its 3-D mills, including the MDX series used for product prototyping and short-run production. To create the prototype or part, this benchtop machine mills away excess material from a solid substrate, a method based on CNC milling. The process is easy, efficient and precise. Prototypes are built with precision and a surface finish that is often better than several comparable 3D printers, and easier than on many CNC mills. The MDX machine is an example of an integrated software/hardware system that is easy to navigate and is effective for intricate applications.
No G-Code required
CNC mills have been around for decades. Initially, these systems required time consuming and often tedious code writing to create the CNC program. Not an easy task–one wrong line of code and a production part is scrap, increasing the overall cost of production. Today, with SRP technology, G-Code programming is largely a thing of the past. Design files can be exported as STL, IGES and 3D DXF from your CAD software and loaded into CAM software for a seamless workflow.
Unlike traditional CNC machines, these 3-D mills are automated to reduce user errors and improve consistency and quality from part to part. There are no complex control panels, and instead the mills come with a user-friendly, easy-to-use computer interface. The wizard-base software walks you through a job to determine the appropriate tool to use. It also automatically programs how fast and deep it will cut, and how fast the tool should turn, depending on the material used. Thus, SRP technology provides full CNC function without the traditional CNC complexity. Even better, today’s SRP mills are affordable and more compact, enabling full rapid prototyping and small lot production right at the desktop.
Flexible material choice
When you are designing a product or part, the end material plays a key role in its function, fit testing, finish and product durability, as well as for structural, thermal and electrical testing. Material choice is another area where subtractive technologies shine. Additive technologies typically require a specific material to be processed, which is often proprietary to the machine. Subtractive methods can process multiple materials. You can choose from ABS, acrylic, aluminum, chemical woods, plaster, styrene, Acetal, Nylon and FDA approved plastics.
Prototyping in one material and then manufacturing in another, as additive systems do, adds an inherent risk that the part will not perform as expected. While additive technologies can handle some thermoplastics, few support materials such as aluminum, which are commonly used in manufacturing molds, products and parts. Also consider that additive systems lay down material in layers, which means the tolerances are limited by the thickness of these layers.
With SRP systems, software and hardware components work for precise, repeatable results. From engineered plastics, resin and wood to non-ferrous metals, an SRP system produces a final product with smooth surface finishes and tight tolerances.
Workflow flexibility and versatility
By bringing SRP technology in-house, you can reduce delays and costs for die manufacturing over outsourcing models, and you are immediately able to implement corrections and adjustments to designs, and have instant visibility and verification of product design. You can explore creative options with full confidence in the accuracy and functional integrity of the prototype
Versatility is also a critical factor. Flexible machines that can handle a variety of jobs are in demand. SRP technology lets you create prototypes, PCB boards and engravings, as well as use the machines for post manufacturing work such as drilling holes or surface milling.
In addition, multiple SRP devices can be used together for Rapid Custom Manufacturing (RCM). For example, a Roland customer in the orthopedic industry relies on an assembly line of MDX milling machines to quickly manufacture custom spinal implants used in spine fusion surgeries. Each part is a custom fit for the patient at hand.
Finally, SRP technology is affordable. The list prices for additive and subtractive devices are roughly equivalent, but operating costs can be lower with SRP systems. The difference is due to the higher material costs and maintenance contracts associated with additive technologies. Our research shows that an SRP system saves an average of more than $20,000 over a 5-year period when compared to the cost basis of a comparable 3-D printer.
Gallery of SRP Applications
The following examples are real-world applications, ranging from visual concept models to prototypes and functional production parts. All were created using Roland SRP technology.
Fan Part: This functional model is used on Roland machines to blow chips out of the cutting area when milling acrylic, wood or aluminum. Once the model was created it was put to work immediately after being removed from the machine.
Approximate part dimensions: 40 mm x 40 mm x 10 mm | Part build time: 1.1 hour
Return on Investment
Acetal Material $9.50
Labor (1/2 hr) $17.32
Total Cost $26.82
Value $199.00
Savings $172.18
Bearing Block Prototype: This medium density tooling board provides fast concept models that are dimensionally accurate. The material lets you create concept models at a fraction of the time of plastics or non-ferrous metals, giving you a dimensionally accurate, smooth surfaced model that will hold up to design reviews. Approximate part dimensions: 165 mm x 67 mm x 40 mm | Part build time: 3.2 hours
Return on Investment
Tooling Board Material $25.00
Labor (1 hr) $34.00
Total Cost $59.00
Value $950.00
Savings $891.00
Hair Dryer Prototype: When the designers wanted to test the fit and finish of a new travel-sized hair dryer, they used SRP technology to produce a prototype that would go beyond concept. Accurate materials, smooth surface finish and tight tolerances gave them an assembly that could stand up to thermal and impact testing.
Approximate part dimensions: 135 mm x 175 mm x 60 mm | Part build time: 12 hours
Return on Investment
Acetal Material $65.00
Labor (2 hrs) $69.30
Total Cost $134.30
Value $1,768.00
Savings $1,633.70
Rocker Arm Prototype: This aluminum rocker arm prototype was an early design model used to test the overall shape and function of a mountain bike part. This prototype was created in production grade material to match the production part and confirm fit, finish and functionality. Approximate part dimensions: 140 mm x 45 mm x 7.5 mm | Part build time: 2.1 hours
Return on Investment
Tooling Board Material $25.00
Labor (1 hr) $34.00
Total Cost $59.00
Value $950.00
Savings $891.00
Gear Prototype: This gear was used as a prototype to test real-world function. This fully operational gear was cut in the exact material used for the final product, which enabled accurate component testing. Approximate part dimensions: 51 mm x 51 mm x 15 mm | Part build time: 3.7 hours
Return on Investment
Nylon Material $5.00
Labor(1/2 hr) $17.32
Total Cost $22.32
Value $199.00
Savings $176.68
Fixturing Prototype: This assembly is composed of several close tolerance parts. The jig required a special fixture clamp that was not commercially available and was quickly created on a Roland SRP milling machine. The acetyl copolymer material will maintain tolerances over the entire production run. Approximate part dimensions: 28 mm x 98 mm x 48 mm | Part build time:4.2 hours
Return on Investment
Acetal Material $20.00
Labor (1 hr) $34.00
Total Cost $54.00
Value $375.00
Savings $321.00
Roland DGA
www.roland.com
