A shop owner shares setup tips that improve manufacturing operations.
CNC programmer Jeff Mauney reviews part specifications in preparing to program Allied Manufacturing Technologies' Haas VF-1 for a second operation on the workpiece.
Multi-axis machining gives shops a number of options when it comes to setup configurations. But how do shops determine the best setup on a job-by-job basis? In some cases, one machine, one setup, does the trick. In other cases, it doesn't.
Consolidating operations into one setup minimizes secondary operations and frees operators from handling and rehandling parts, and possibly damaging them in the process. It also eliminates variables associated with performing subsequent operations, where parts must be referenced properly from previously machined dimensions.
Obviously, there's a lot to be said for the idea of feeding material into a machine and having a finished part drop into a bin or onto a conveyor. No secondary operations, no burrs, no handling — just push the button and out comes a perfect part. However, such one-op machining is usually most profitable when running higher volume jobs, where trained operators, dedicated tooling and gaging, and well-established tool-life studies streamline and maximize the production process. In many shops, there's a mix of high and low-volume production. What factors, then, should be considered when jobs can be set up either conventionally or using the multi-axis tooling functions of a machine?
Profit, profit, profit
With razor-thin profit margins being cut further by off-shore competition, and the continued shortage of experienced help, shops must run profitably to survive and grow. Jobshops, especially, have to run a part profitably the first time, since there may never be a second order.
An educator recently proposed that shop owners train setup people by concentrating less on profits and more on helping employees gain experience. In his view, those with less experience should have more latitude to experiment with setups, so they might learn. He believed that if 50% of these experiments were successful, the shop owner would eventually get a good return on the investment.
This idea doesn't translate well to the shop floor, where just-in-time manufacturing, customer-driven cost savings, and expedited deliveries define the machine tool battleground of the jobshop. In fact, the divergent view of novel setups versus tried-and-true, "get-the-partdone-fast-and-out-the-door" setups is at the core of many heated discussions between shop owners and setup personnel.
But the cold, hard truth is that unless certain factors are deliberately taken into consideration at the outset, setups can gradually drain a company's resources and ultimately cause it to lose its competitive edge.
These factors include the quantity of parts being run, the complexity of the parts, and the dollar amount of the job itself. Shops should also take into account machine capability (is it capable of performing designated secondary operations?), availability, and backlog.
Other elements that come into play are the experience of the operator running the job and the cost of using tooling not generally stocked in the shop. There's also the additional, non-reimbursed costs of tooling and fixturing associated with condensing operations as opposed to running a job conventionally. Finally, shops should look at the total setup time and cycle time involved in one setup versus many.
The goal is to run a job — producing quality parts — in the shortest time possible. If an order is for five pieces, and the part is a 1.00-in.-diameter shaft with a 0.187 2.00-in.-long keyway, should a shop turn it on a manual lathe and mill the keyway on a manual mill? Or would it be faster to program a multi-axis turning center, set up the machine, set up the barfeeder and the live tools, and then run the part complete? The setup that takes the part from raw material to finished product in the least amount of time — including the setup person's time — is the most profitable and practical.
As there are only five pieces, a setup person would most likely run this job. However, if production warrants the use of an operator, the next question is: Who will run the job — a trained operator or a trainee? Even among trained operators, levels of experience vary tremendously.
If using a trained operator, shops may find the best solution involves setups where secondary operations are condensed. If, however, the operator is a trainee, the shop might set up the job in two stages to accommodate the opera-tor's current experience level.
In choosing the machine, there are times when a new, fully tooled turnkey machine is the most profitable solution, especially when running high-volume, brutally competitive contract work. For lower-volume production, though, existing machine tools are usually specified.
Keep in mind that while a machine may have multi-axis capability, it isn't always practical and profitable to use its full potential every time. Backlog on the machine, expensive nonreimbursed fixturing, additional tooling costs, and lengthy programming and setup time may mandate secondary operations.
For example, will running a part jeopardize deliveries of other high-dollar orders that can only be produced on the designated multi-axis machine? Also, if there's a backlog on a $150,000 multi-axis CNC lathe but open time on a lower-cost CNC mill, is it more profitable to run the job in several operations on the less expensive mill, minimizing backlog and maximizing machine tool usage? Again — quality, operator experience, complexity of the part, and other factors should be carefully weighed.
The proof is in the production
To show how different setups affect a company's bottom line, Allied Manufacturing Technologies, Lincolnton, N.C., processed two parts using two different setups. In both cases, the production run was 1,000 pieces on a VF-1 vertical machining center from Haas Automation Inc., Oxnard, Calif.
In the first setup, described in the chart below, the job was processed in two operations, with the operator running the parts while the setup man programmed the second operation using the background edit feature of the Haas control.
In the second setup, the job ran in one operation using a Haas HRT 210 rotary table.
There is a point at which the second setup along with associated fixturing costs — even if not reimbursed — is more economical, especially if a customer repeats the order on a regular basis. Having the option to run a job using different approaches gives shops choices that can increase profits. The key is having a balanced approach, and giving careful consideration to all the factors associated with successful completion of the project.
|Step||Process||Setup time||Cycle time|
|2||Set up vice and program machine to contour part||3 hr||80 sec each|
|3||Program 2nd op drill/tap in background edit while operator runs job||0.5 hr|
|4||Set up vice for drill/tap, check parts||0.5 hr|
|5||Run finished parts||120 sec each|
Total setup/programming time: 4 hr
One-operation setup using rotary table
|Step||Process||Setup Time||Fixture Time||Cycle Time|
|1||Design & build two fixtures (load one, unload the other)||40 hr|
|2||Set up fixture, rotary table and program machine||10 hr||100 sec each|
Total setup time: 10 hr (2nd run is less since program is already written)