As Seen in Die Cast Engineering September 2016
Vic Jost, President
Jost Machinery Company Ellisville, Missouri
NADCA is an excellent source of information in the world of die casting. Smart manufacturers are always looking for ways to be more competitive and more profitable. Worldwide competition requires that every¬one improve their knowledge and skills every day in order to better serve their customers. The marketplace demands that each person must do the work that used to be performed by two or three people in the past. These efficiencies come from personal effort in plan¬ning and organization, but also from better tools such as computers and automated manufacturing systems.
As we develop new manufacturing processes for post-casting/secondary operations, we frequently recall success stories where the key to success was the breakthrough idea that brought everything together when designing a die casting manufacturing process. Experience is a great teacher and many old ideas can be used again and again. This article describes “(7) Tricks of the Trade” that incorporate ideas that can be successfully pulled from past projects and recycled into your future projects.
Ideally die cast manufacturers would like to just cast and trim their castings “as-cast” and not have to deal with the machining, quality control, inspection and as-sembly operations, etc. It would be great if life was that simple, but in the author’s experience most modern die castings require additional secondary operations due to their use and function... and this is a good thing. There is far more money to be made in the secondary opera-tions... if you do them right!
Automated trimming, machining, inspection, test¬ing and assembly operations can make or break a die casting job and require thoughtful planning and capital investment. Thankfully, there are many “Tricks of the Trade” available to you. This article passes along some of those ideas from the author’s experience in the die casting industry. Hopefully you will find one or more of them valuable to you.
Mechanical sliding tray unloaders are simple and cost effective. No electrical, air, or hydraulic actuation is required with the actuating arm connected to the ram, the tray moves under the die to catch the parts. A compound die will place the castings on the tray and unload them into bins. You benefit from the increased speed of your trimming operation and the added safety built into the system.
It is possible to trim each cavity, locate each cast¬ing, inspect with camera and sort good parts from scrap castings. This type of automation is built around a servo actuated tray with a compliment of conveyors, clamps, cameras and controls specially designated to automate these operations. These types of systems are custom built to automate the processes that must be performed. They work well in high volume die casting because they handle fast cycle times and multiple secondary processes all with little operator involvement.
Simple precision machining operations on your die castings are done best with simple precision machines. Simple special machines can give you the competitive edge when you are machining die castings. They are an excellent alternative to multiple CNC machines. In fact, many of these machine are equipped with CNC controls, but only for the functions required on the machine! They can be optimized with precision work-holding devices that can be unloaded/loaded in seconds by operators, or in conjunction with automated material handling such as robots with conveyors or dedicated material handling. Custom cutting tools are another good trick of the trade because they can cut multiple surfaces simultaneously to save time in the cut while machining everything concentrically to close tolerances. These tools can be carbide or diamond inserts with high pressure thru the tool coolant, guarding and chip removal to optimize your machining operations. In fact, with good design practices you can optimize each of the critical components on special machines, especially fixturing, cutting tools, tool monitoring, quick change tool holders, machine tool components, best workflow, inspection, material handling, chip removal, lubrication, safety and all of the controls on the machine. Simple special machines can turn a bad job into a good job or even make the difference whether you get the job at all. They are production systems designed and built to machine production parts.
This aluminum die cast bracket only needed to be cast, trimmed and tapped, but there were three dif¬ferent size taps at three different elevations. It was originally tooled on a horizontal machining center with pallet changer but it was too slow (only 30 PPH) and that HMC was needed for a casting that required CNC operations.
The solution was an individual lead screw spindle tapping machine that could tap (300 PPH) with manual material handling. The part is loaded on the cast datum directly in front of the taps. The fixture automatically clamps the castings and senses the part presence. Then each spindle feeds to depth and returns to home and the clamps retract. There are three M10 Thru, two M6 Blind, and one M8 Thru holes for a total of six tapped holes with every cycle of the machine.
Special tapping machines like this can be ten times faster than CNC machines, 75% LESS than the CNC, run in a die cast department by unskilled operators and produce consistent quality.
Companies that machine large die castings such as automotive, large engine, small engine, agricultural, elec-tronic, computers, cable TV, appliances, etc., are challenged to produce quality machined castings at an affordable price. CNC machining centers are frequently the first choice because they are extremely accurate, flexible and offer high feeds, speeds and rapid movements, but they only have one tool cutting at a time. Multiple spindle drilling and tap¬ping machines are a good compliment to CNC machines because they can drill or tap every hole in every face of the die casting automatically. This also works well when you are just tapping. Many times the CNC operator runs a mul¬tiple spindle machine in a cell within the cycle of a CNC machine. Manufacturers benefit because of the cost savings, lean manufacturing, improved work flow in the cell, floor space savings and labor support savings. This creates a major opportunity to make more money on the die castings you produce and expand into new opportunities in the future.
Automatic assembly operations for die castings can be simple or complex, just like the trimming and machining operations. The machine in Trick #6 automatically swages a die cast hub with a grinding disk. It uses an automatic drilling unit with a variable frequency drive hydraulic power pack, linear encoder positioning sensor and HMI programmable controller. Feed rate, swaging force, dwell force and position are continually monitored for consistent operation and repeatability. This process greatly improved the old process to upgrade product quality, reduce cycle item, and increase the overall efficiency of the manufacturing cell.
Automatic assembly can include:
· Pressure testing
· Screw drivers
· Automated material handling
· Conveyors and indexers
Each of these is chosen and integrated into the system because it is needed and to improve the profitability of the operations.
Die casting is an amazing manufacturing process that is growing in use and finds more production applications every day. Precision milling and boring, drilling and tapping, pressure testing, automated assembly operations, etc., are commonly required in the finished parts. Our “Tricks of the Trade” are examples of some of our post-casting/secondary operation solutions. You can review additional “Ideas That Work” on our website, including videos, at www.jostmachinery.com.
Give us a call when you are looking for help with your secondary operations. We have many years of experience helping Die Cast Companies develop their secondary operations. You don’t have to reinvent the wheel - we have “The Tricks of the Trade”.
About the Author
Vic Jost is President of Jost Machinery Company in El-lisville, MO. He is available for consultation for trimming, machining and assembly systems for companies making die castings and he has been a member of NADCA for many years. Many consider him to be a Thought Leader due to his ability to put together the Jigsaw Puzzle of random bits of manufacturing details and develop working solutions for their automated manufacturing systems.
www.diecasting.org/dce SEPTEMBER 2016DIE CASTING ENGINEER
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