Castings on Stunning Display
Christie uses dozens of cast components in its numerous lines of high-definition projectors found in movie theaters, boardrooms and public displays around the world.
Nicholas Leider, Associate Editor
(Click here to see the story as it appears in the February issue of Modern Casting.)
The common axiom “no detail is too small” carries enough truth to have become a part of business parlance. But for Christie, one of the world’s largest manufacturers of complex audiovisual projection systems, little details can have big consequences.
Consider the challenges for Christie engineers in complex, tight tolerance, abstract designs, where high-definition projection systems can turn the entire façade of a massive resort hotel into a blank canvas, or the precision required for high-definition wall-projection systems in command centers monitoring electrical grids. To allow these systems to operate precisely and reliably, Christie depends on castings.
With more than 75 cast parts in its diverse line of products, the company works with metalcasting facilities to produce more than 20,000 components annually. At Christie’s North American design and manufacturing hub in Kitchener, Ontario, Canada, just outside of Toronto, a staff of 750 produces between 1,000 and 1,100 projectors a month at the 105,000-sq,-ft. facility.
“High quality castings which meet Christie’s design specifications are critical to the manufacturing assembly process, quality and test performance of projectors, as well as overall customer satisfaction,” said Paul Tierney, senior manufacturing manager, Christie.
Lights? Cameras? Castings
With projection systems operating in a wide range of end uses, such as 3D digital cinema and corporate presentations, Christie uses a number of materials and processes for its castings. Larger components—for example, the baseplates that support units weighing as much as a 280 lbs.—are sand cast in either stainless steel or aluminum. Casting these components reduces cost versus high-precision welding and machining. Compared to those machined from stock, the cast metal components offer improved mechanical and physical properties at a reduced cost.
Within the projectors, a number of components must meet high standards for form, fit and functionality. The lens mount, for example, could produce myriad technical problems if it did not meet exact standards.
“High precision is essential to the function of Christie’s projectors,” said David Kiers, director of engineering at Christie. “Critical features are machined after casting to hold tighter tolerances when required.”
Many other applications, such as those related to the projector’s processors and microchips, require much smaller components with significantly different design considerations. In addition to aluminum, steel and magnesium, zinc is used for applications with lower weight considerations.
In total, Christie uses components produced via diecasting, permanent mold, sand and investment casting processes. When identifying a possible candidate for conversion to a casting process (or redesigning an existing casting), the selected process is based upon many factors including cost, expected volumes, choice of materials, degree of complexity, visual cosmetics and final appearance.
Engineering must overcome two traditional barriers to develop a conceptual design to obtain a cost-effective, feasible casting. The first challenge is developing a relationship with metal casting suppliers that encourages and fosters early, effective and ongoing communication.
“Christie aims to incorporate metalcasting facilities early in the design process. There’s a high level of collaboration,” said Jim Steward, Christie’s commodity manager. “Identifying and eliminating problems early in the process can help streamline progress and control costs by limiting design iterations.”
The second challenge is inherent in the supplier-customer relationship, with the two engineering teams having to marry different considerations in a part’s final design.
“Typically, the product designer is focused on issues such as the part functionality, operating environments, failure modes, secondary operations and cosmetics,” said Mark Ratcliffe, manufacturing engineer. “The engineers who will design the casting and its tooling, on the other hand, will be concerned with material flow, gating and coring issues, part shape variability, hot and cold spots, shrinkage, parting lines, solidification patterns and porosity.”
Recently, Christie experienced some problems with a cast magnesium light engine enclosure in one of its digital projectors that had been produced in Asia. Due to significant challenges, Christie began to reexamine the casting’s sourcing strategy.
“There were a few simple goals with the project: to identify and reduce design constraints as well as cost drivers where practical, while ensuring such changes would not impact any mating parts,” said Adele Evans, director of global supply chain management.
The design for the problematic casting was sent to one of Christie’s existing casting suppliers for quotation purposes. During a phone call after receipt of the drawings, engineers discussed some technical issues for the enclosure, which had been a two-piece casting produced via thixomolding, a process of injection molding of a semi-solid alloy. In exploring possible solutions, the two sides pursued a concept of the housing that would turn the component into a single magnesium die casting.
Within a few months, collaborative technical discussions and flow analyses were taking place for the one-piece design. Reducing the component to a single casting would reduce part count ratio, improve physical and mechanical properties, simplify inventory management and minimize required machining.
“With the original design, not only did you have a two-piece assembly, which is more expensive, but you also had the assembly component to it,” said Eric Voss, Christie advanced product developer. The two-piece assembly also could “result in potential final assembly issues on the production line.”
By simplifying the assembly into a single diecast component, Christie and its supplier decreased shipping, tooling and machining costs while improving the casting design. The developments also improved dimensional accuracy and cut the component’s weight 8%.
Seeking Out Suppliers
Through past experience and education, Christie’s engineering department includes experts with casting experience to help identify potential candidates for the manufacturing method. Once a part is identified as a potential casting (or a redesigned casting), Christie’s purchasing department tries to identify metalcasting facilities from its current qualified supplier list. If one cannot be found, Christie then begins its search with existing industry knowledge, internal and external research and trade publications.
When pursuing a new supplier, Christie takes a number of steps in identifying and selecting potential metalcasting facilities, including:
- Researching firms via available public data, Dun & Bradstreet reports and internal supplier questionnaires.
- Visiting and auditing vendors’ capabilities, financial health, industries served and business systems and practices.
- Entering into a non-disclosure agreement and proceeding with an RFQ on a limited number of parts.
- Selecting a supplier based on audit, business, capabilities and cost performance.
With Christie manufacturing locations in both Canada and China, geographic limitations rarely present problems. Parts are sourced from a number of manufacturers across the globe. Also, considering the limited size of many castings, shipping costs are a consideration but rarely the determining factor. (In such cases, larger parts typically will be sourced more locally.)
To maintain standards with its suppliers (casting and otherwise), Christie has a proprietary auditing program with extensive questioning and scoring mechanisms for evaluating and rating suppliers.
“Suppliers are audited through questions for current and historical performance in commercial stature, financial standing, growth, capital investments, customer base, document and order process control as well as quality and design procedures with practical evidence,” said Steward. “Engineering and design capabilities and third-party information also are obtained and reviewed in the evaluation.”
New product turnaround time and production lead times play a critical role in meeting project launch dates and ongoing inventory cycles. Considering these revolving deadlines, Christie has developed its own rapid prototyping division, known as Hyphen. Established in 2000 and officially opened to the public in October 2012, Hyphen offers a number of prototyping services, including stereolithography (SLA), CNC machining and selective laser sintering (SLS).
Christie officials expect castings to continue to play a vital role in the development of projector technology. Casting capabilities and materials continue to improve, including further weight reduction and improved performance, meaning the company will continue to provide an example of how cast metal components can play a vital role in producing big results.