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Stereolithography, SLA

Stereolithography (SLA) was the first rapid prototyping process that became widely available to consumers and is still the most common process used in rapid prototyping today. Developed by 3D Systems in Valencia, California, stereolithography (SLA) was invented in 1986. Stereolithography (SLA) uses a UV laser to photo-cure large vats of epoxy based resin in the shape and form of an electronic 3D file. As the stereolithography (SLA) laser moves along the vat three dimensional parts are built layer by layer on a tray that sits just below the top of the resin line. The additive layer characteristic of stereolithography (SLA) allows the technology to build complex parts and geometries that may not be obtained, or cost effective, through other avenues such as machining. Once the parts have been completely built in the stereolithography (SLA) machine, they are removed from the tray and placed in a post curing chamber for final photo-curing.

After the stereolithography (SLA) parts have been completely cured there are a variety of finishes that can be done to them depending on desired application or use. Generally, stereolithography (SLA) parts are thought to have better accuracy and surface finish than other popular rapid prototyping processes. Since stereolithography (SLA) parts can be sanded, primed, painted, or plated a higher level of smoothness and appearance can be achieved than what comes directly out of the machine. After 20 years of stereolithography (SLA) being on the market there is a wide range of materials with varying mechanical properties that allow stereolithography (SLA) parts to further try to mimic mainstream engineering grade thermoplastics. The overwhelming advantage stereolithography (SLA) has is the ability to create high quality, fine detailed parts with wonderful aesthetic qualities in a short turnaround time.

Other added benefits of stereolithography (SLA) are:

Highly detailed parts with a smooth finish
Very accurate tolerances even down to thousandths of an inch
Large array of materials ranging in rigidity, clarity, color, detail and temperature deflection
Capability to use parts for short run low temperature tooling
Can be used for light duty function
Variety of finishing capabilities such as painting or plating for show presentation or demos
Rapid turnaround times of most parts typically within a few working days

Since its invention in 1986, the Stereolithography (SLA) process has made great strides both in machinery and materials. There are now over 10 different types of stereolithography machines in circulation with build parameters ranging from small platforms (5”x5”) and low laser power to large platforms (60”x20”) with faster, more powerful lasers. The diversity in size of the stereolithography (SLA) machines allows for easy production of small, fine detailed parts or larger, more dense geometries. In addition to improved machinery, stereolithography (SLA) materials have also come along way since their birth. Stereolithography (SLA) resins are now made to mimic a wide array of production plastics such as ABS, Polypropylene, and Polycarbonate. There are even some stereolithography (SLA) materials that are quite soft and flexible ranging from 45 shore A to 80 shore A in softness.

Stereolithography (SLA) parts can be used for a number of different types of applications. First, and probably the most common use for stereolithography (SLA) parts, is functional prototypes. Many users want stereolithography (SLA) models to mimic their production parts and so they use the parts for functional testing and evaluation. Secondly, stereolithography (SLA) parts can be used for concept models. These stereolithography (SLA) parts are typically finished to a higher, smoother level and quite often painted for presentations or sales and marketing purposes. Another application for stereolithography (SLA) parts is casting patterns. The stereolithography (SLA) build style known as Quickcast® is commonly utilized to create patterns for the investment casting of a metal part or parts. Short run tooling, commonly called RTV, and silicone molds for urethane casting also use stereolithography (SLA) parts as master patterns. In addition, stereolithography (SLA) patterns are used in the plaster, sand, and spin casting processes as well.

A fourth application for stereolithography (SLA) is end use production parts. With the large variety of different types of stereolithography (SLA) materials now available it is becoming more and more common for end use production parts and even assemblies to be manufactured right off of a stereolithography (SLA) machine. While it is not always the right solution, stereolithography (SLA) does offer a tool-less alternative to very costly machining and other manufacturing methods such as machining. Finally, rapid tooling is yet another of the applications that stereolithography (SLA) is well suited for. The term Rapid Tooling is usually associated with the process or processes used to create limited-run tooling directly or indirectly from a rapid prototyping machine, including stereolithography (SLA) systems, and subsequently molding or casting end-use components and assemblies. For many types of parts, rapid tooling is an excellent choice for initial test production, low-run production or bridge tooling until the conventional tooling is delivered. This allows a product’s time to market to be much quicker and leaves open the possibility to make critical design changes without the expense of cutting new production tooling. At Harvest Technologies, we are always willing to work with a customer to explore the use of stereolithography (SLA) for production or rapid tooling applications. If you have a unique stereolithography requirement, please feel free to contact us and we will gladly look at the possible options for production of your part(s).

Stereolithography’s History at Harvest Technologies

Value Added Service
In 2001, after six years of conducting business primarily using selective laser sintering (SLS), Harvest Technologies was looking at ways to diversify itself and add value to its service business. Bringing stereolithography (SLA) in house was the obvious choice of technologies to be added. Harvest had been outsourcing some stereolithography (SLA) to other service bureaus so a customer base was already beginning to develop. The addition of stereolithography (SLA) under our own roof was beneficial in several ways. Harvest was able to capitalize on the service it presented to its customers by cutting down on lead times and cost that the stereolithography (SLA) outsourcing was demanding. Bringing stereolithography (SLA) in house allowed Harvest to turn out a higher volume of parts quicker and at a lower cost to customers, as well as, ensure the parts met the high quality standards that Harvest prides itself on producing. It also seemed like a wise addition in that stereolithography (SLA) is a complimentary technology to the selective laser sintering technology that Harvest has hung it hat on now for over 10 years.

Initially, the focus of the stereolithography (SLA) addition to Harvest’s line of rapid prototyping services was on the more difficult and complex parts that the stereolithography (SLA) technology is able to produce. The first stereolithography (SLA) machine that Harvest bought was a 3D Systems Viper Si2 which allowed for high or normal resolution parts to be built in the same machine. Since Harvest was primarily focused on complex parts that had fine details the high resolution build style was mainly used. As time has gone by, and the stereolithography (SLA) business has grown, Harvest has gotten into doing build styles of all types while remaining a large provider of high resolution parts.

History of Growth
The in house addition of stereolithography (SLA) to the list of rapid prototyping services at Harvest Technologies has definitely proven to be a wise decision. Stereolithography (SLA) was not only a nice complimentary to Harvest’s already expanding selective laser sintering (SLS) business but it has proven to be a growing business sector of its own. Harvest now has six stereolithography (SLA) systems in place with plans to add more in the future. After Stereolithography (SLA) was added in the fall of 2001 it was just five months later that a second stereolithography (SLA) system was brought in. Since then, Harvest has added at least one stereolithography (SLA) system each year to bring the total to four Viper Si2 systems, one 5000 large platform system and Harvest’s newest addition a 7000 large platform stereolithography (SLA) system. The latest machine addition happened in the first quarter of 2006 and more stereolithography (SLA) machine additions are planned, possibly as early as fourth quarter 2006. Obviously, with all of the machine additions at Harvest, the stereolithography (SLA) capacity has greatly increased. With the first machine Harvest had 100 square inches of stereolithography (SLA) capacity. That has now been increased to 1200 square inches of stereolithography (SLA) capacity which allows Harvest to produce a higher volume of stereolithography (SLA) parts in a shorter turnaround time and at a lower cost to our customers.

In conjunction with adding stereolithography (SLA) machines and capacity, Harvest has also added and upgraded the stereolithography (SLA) materials it uses. With each machine addition a subsequent stereolithography (SLA) material addition has come as well. Harvest has gone from running one stereolithography (SLA) machine dedicated to one specific material to running six different materials with the ability to swap vats in several different machines. This allows Harvest to meet customer’s stereolithography (SLA) needs by putting the higher demanded materials in specific machines when necessary. Additionally, in keeping with Harvest’s desire to be on the cutting edge of the stereolithography (SLA) technology, three of the six materials being used have all been added since the beginning of 2006. Harvest continually takes part in beta programs for testing new stereolithography (SLA) materials to stay abreast of what is available in the stereolithography market.

More Than Just Stereolithography (SLA)
Effective stereolithography (SLA) prototyping requires meeting each customer’s specific needs by matching the right materials and build styles to the desired production outcome. In addition to the in house stereolithography (SLA) and selective laser sintering (SLS) capabilities Harvest has, we also utilize a quality network of partners to provide additional services. Below is a list of some of the services we provide through our partners:

RTV tooling and urethane casting
Investment casting, plaster casting, spin casting and sand casting
CNC machining and milling
CAD modeling and design engineering
Various other 3D printing and rapid prototyping technologies and processes

Our rapid prototyping technologies, stereolithography (SLA) and selective laser sintering (SLS), allow you to save time and money by decreasing your time to market, and avoiding costly modifications to production tooling. Multiple versions of stereolithography (SLA) and selective laser sintering (SLS) prototypes can be produced and evaluated in days, versus weeks, allowing time to refine designs. In short, Harvest Technologies can save customers time and money, while helping them reach their desired goals.