Upgrading machine tool technology — either by the major retrofit of existing machines or purchase of new equipment — is often an expensive proposition requiring non-productive downtime and months or even years to realise a return on the capital expenditure.
However, Indelac Controls discovered an easy way to boost production and maintain tight accuracy requirements for its electric actuator housings, while not breaking the bank on new machines or costly upgrades. By using bolt-on trunnion tables, the shop managed to cut cycle times by 40 percent and eliminate batch processing that required work in process.
The tables were installed in minutes on the fourth axis indexers of the company’s two Haas VF4 vertical machining centres, producing a 100 percent ROI within days. The two machines now mill, drill, tap and even do light contouring on 319 aluminium castings with 66 percent fewer part setups.
Time-consuming part locating, previously required to meet accuracy requirements of 0.0005”, was also eliminated without compromising part quality.
“We were pleasantly surprised to see that something so simple could exploit the fourth axis on our machines and have such a dramatic impact on our business,” said Bill Robinson, shop foreman for the company. “We can now produce the same number of parts in a day that may have taken a week using our old methods.”
Fewer Setups = More Parts
The company manufactures a variety of electric actuators. Today’s actuators have advanced functions that go beyond simple open and close capabilities. Some are packaged with position sensing equipment, torque sensing, motor protection, logic control and digital communication. These hi-tech functions make accuracy of the housings critical to proper function, so the company has always produced its machined parts with an accuracy of 0.0005”, even when the process methodologies made this time consuming and labour-intensive.
The company’s need for accuracy required frequent indexing off of previously machined features using ‘homemade’ fixtures, clamps and angle plates. “On top of everything else, locating on cast parts is more difficult because the surfaces can vary greatly from part to part,” said Clay Huff, machinist at the company.
Multiple part setups had driven cycle times at the company up to 50 minutes or more and parts were batch processed and created stage by stage over a series of operations. “Some of our housings require machining on all six sides, and with our previous workholding methods, that meant six separate setups,” said Mr Huff.
Make More, Sell More
To improve cycle times in its machine shop, the company purchased two custom-made tables and four fixtures, as well as a standard model Stallion 9\23 — a double-sided table with quick-change plates — that is compatible with most vertical machines. The quick-change plates allow one-minute changeovers and 0.0005” repeatability.
The trunnion tables and fixtures use locator pins to position and hold the part, ensuring part-to-part consistency. Mr Huff routinely checks every fifth part with a CMM to close the quality control loop. Fewer setups and part handling have made hitting the accuracy tolerance a faster, easier enterprise. “With the old fixtures, we had to indicate repeatedly to make sure we had it right. My life is a lot less stressful now that we have the trunnion tables,” he added.
With the trunnion tables, the company was able to implement continuous production and improve its cost-per-part numbers by decreasing manufacturing costs and increasing finished part production. “Our cycle time is down to about 30 minutes with the trunnions compared to 50 minutes or more with our old fixtures, and we get a finished part off every time we hit the cycle start button,” said Mr Robinson. “We’ve reduced cycle times and eliminated WIP, so if a quick-turn order comes in we can setup the machine, run the part and get it out the door.”
A Small Investment With Big Results
Ninety percent of the company’s parts can be run using the workholding devices, and the days of manual clamps, angle plates and plugs are over at the shop.
“Compared to purchasing a US$300,000 five-axis horizontal machine, spending a few thousand to get the most out of our four-axis verticals is the deal of the century,” said Mr Robinson. “Sometimes the simplest, least expensive method produces the desired results and that’s what we found with these trunnions.”
TrunnionTable: Turning Vises Into Virtues
Stallion 9\20 and 9\23 tables allow users to exploit the rotary fourth-axis capability of horizontal and vertical machining centres, and deliver a low-cost path to higher productivity and improved accuracy.
The bolt on trunnions are work-ready right out of the box and the trunnion fixtures are engineered to bolt on to any machine’s rotary indexer, allowing operators to precisely mill, drill, tap and contour up to three sides of a part in one setup without special fixtures. Heavily ribbed cast iron construction provides high rigidity and durability, which are needed to withstand long-term repeated use in demanding shop environments.
Built for precision as well as durability, the US-made tables have 0.001” flatness over 23 inches and 0.001” squareness to the faceplate.
