The size of a rotary indexing dial depends on the product to be assembled and the number and type of stations needed to assemble it. For automated assembly applications, dials range in size from 18 to 100 inches in diameter.
Products assembled on rotary indexing dials are small. Most fit inside a 6-inch cube and have less than 15 parts. Ideally, the product’s parts should be assembled from above, with simple up and down motions.
Most assembly operations can be performed on a dial, including pick-and-place, screwdriving, crimping, pressing, labeling, ultrasonic welding, dispensing and ultraviolet curing. SCARA robots, machine vision systems and electrical testing can be incorporated into dials, and products that require micron-level placement accuracy can be assembled on dials.
Each assembly process on a dial should take seconds, not minutes, and all processes should be as close together in time as possible. Production rates with rotary dial systems vary, depending on the number and type of processes included. Each system’s index time will be limited by the slowest process on the dial.
A rotary dial system built recently by Edgewater Automation LLC (St. Joseph, MI) is a good example of just how productive and flexible these machines can be. According to Doug Wierenga, regional manager of Edgewater, the system was built to assemble an automotive switch with seven variants. For more information, call Edgewater Automation at 269-983-1300 or visitwww.edgewaterautomation.com.
Describe the system. Eight-station rotary indexing dial machine for programmable, point-to-point soldering of electrical switches to circuit boards. Because of the number of current and future model variants to be assembled on this machine, a high degree of flexibility and programmability was required. The switches are soldered to the boards by four SCARA robots. Each robot occupies one station around the dial. Each robot is programmed to solder up to four points on each assembly. Each switch has nine to 16 solder points in various locations. Future models can be accommodated with additional robot programming and, if necessary, new fixtures. The machine requires one operator to load and unload the parts.
What are the dimensions of the finished assembly? 80 by 60 millimeters.
How many parts are assembled to complete the product? Two. A switch assembly and a printed circuit board assembly.
What materials are the various parts made of? Plastic housing, tin-coated terminals and a PCB.
How are the parts fed? One operator loads and unloads components at the first station.
What is the production rate? Seven to 13 seconds per part, depending on the total number of solder joints in the assembly. On average, the machine solders one joint per second.
What was the most challenging aspect of designing and building the assembly system? The main challenge was achieving the desired cycle time on the soldering process. With input and support from each member of the project team at Edgewater Automation, the customer and the component suppliers, we were able to solve that problem.
Editor’s note: Whether you’re a systems integrator or the in-house automation team of an OEM, if you’ve designed a system that you’re particularly proud of, tell us about it. Send an e-mail to John Sprovieri, editor of ASSEMBLY, at email@example.com, or call 630-694-4012.