Some jobshops purchase machine tools based on current workload only. However, when unexpected, high-volume jobs come in, these shops can quickly find themselves unable to keep up. For these situations, gantry-style loaders that retrofit to existing machine tools could be the answer.
Wes-Tech Automation Systems manufactures and installs such loaders. The Lincolnshire, Ill., company retrofits about 85% of its turning-center loaders to older, existing machines. In most cases, shops call with emergency situations that require immediate integration of automated part loading. The challenge is to accomplish this with little disruption to the customer's production flow.
Made to retrofit
Wes-Tech conducts a 24-hr runoff prior to shipping its gantry loaders. In testing, the units load and unload a customer's actual part into a simulation of the intended machine tool. At their destinations, loaders need only mounting, leveling, and integrating.
"Because the loader is a gantry-style," says James Gondek of Wes-Tech, "it never touches the machine tool, so technicians can do the installation while the machine produces parts in a manual mode." Other loading systems, he adds, can obstruct the front of a turning machine, making it difficult for manual operation. Since Wes-Tech's gantry system is completely above the machine, operators can easily get in for manual runs, insert changes, offset adjustments, and so forth.
During integration, the machine-tool program does not change. Loaders use four M-codes or signals inserted after the machining process that provide communication between the machine's control and the loader's. Cycle time for the loader is usually set about 15 sec faster than the customer's machining cycle time. This ensures that the loader is waiting on the machine and not the other way around. Wes-Tech's control will interface to any type turning center control with 24-V output.
Also, the use of standard, interchangeable components makes retrofitting painless. Modular designs let Wes-Tech customize its loaders because not every shop loads sawed blanks. For instance, a shaft gripper is easily interchanged for a chucking gripper, and the standard gripper can do the work of several grippers by handling diameters up to 6.700 in. with a single-screw adjustment. By making minor changes to the finger tooling, loaders can accommodate almost any part up to 150 lb.
Wes-Tech determines which system to implement based on the customer's average raw part weight. Its model TCL 210, for instance, moves two 10-lb parts, its TCL 220 handles two 20-lb parts, its TCL240 tackles two 40-lb parts, and on up to the TCL 270 and 2150.
No one wants to be a human part loader
When S&S Machine Inc. went shopping for a second Mazak Quickturn turning center, it had no idea a huge job was on the way, and so it decided against the automatic loader option. At the time, the Union Grove, N.C., jobshop was running a couple of hundred gear blanks and just wanted a second machine. Suddenly, though, its customer upped the order to 3,000 gears a week. Machine operators then had the monotonous job of loading machines for three shifts, seven days a week. "The workers were human gantry loaders," comments President Dorian Swanner.
An operator had to have a raw blank in one hand, pick the finished part out with the other, load the raw blank, step on the peddle to close the chuck, and then finally hit cycle start. During the short 55-sec machining cycle time, the operator also had to inspect the part that just came off the machine.
Machines ran constantly to meet the quota, but sat idle when the operator took short breaks. For lunch or dinner breaks, another operator was called in because the machine couldn't sit idle.
When Swanner met with Wes-Tech Automation Systems, he told them the gear job could end at any time. So he did not want an automatic loader package tailored exclusively for that job. It had to have some flexibility for future jobs with different part shapes and sizes. Wes-Tech retrofitted a TCL 210 to one of S&S's turning machines.
The loader not only maintained the weekly 3,000-gear pace, but also increased production speed by 33%, allowing S&S to complete the quotas running only two shifts/week instead of three. Operators simply load the 210's pallet carousel, and after the last part is run, the machine automatically powers off.
Swanner's prediction was right — the customer decided to take the gear job back in-house, but the loader isn't out of work. Presently, S&S runs about 100 different jobs using the loader, most of which can have anywhere between 200 to 3,000 parts each. According to Swanner, the loader is versatile and easy to set up for these different parts.