CNC Programming for Batch Machining

Today, we’re going to answer a question that we get a lot – how do I program for batch machining?

What is Batch Machining?

“I need to make identical parts in one fixture. Should I take first position as a program zero or do I need to find zero point for each part and store to the position memory?”

VIDEO: Shows batch machining of aluminum parts using a vacuum chuck to hold sheet material.

The concept of batch machining is very simple – running the same part multiple times in one cycle to boost your machine efficiency. However, when it comes time to execute on this plan, it can get a bit complicated. Most CAM software packages can duplicate toolpaths over an array of parts but have the major downside of posting very large files, which results in a longer setup and loading times. You can also program a macro to run a toolpath again after moving an incremental amount and resetting the zero point. However, this involves even more time behind the keyboard laying out the program structure and slowing you down from making chips. The same can be said for a program that has multiple work offsets stored to memory.

Batch Machining with Multiple Execution Function

Luckily, the engineers at DATRON realized that this a major pain for machinists and have alleviated it with the most recent software update to the next control (v2.10) with a function called Multiple Execution.

Multiple Execution works in two ways: Machining multiple parts in a matrix (or grid pattern), or with Work Piece Zero Points (individual work offsets).

From here, you can activate Multiple Execution, and choose “In Matrix” for layout mode. At this point, simply define the distance between your parts in X and Y, and the number of pieces to create in each direction. From this input, information will be automatically generated on the size of the workpiece and the total number of parts to be milled. At this point, click OK and proceed to run in simulation to verify the correct spacing.

Batch Machining Using Work Piece Zero Points

The other method of executing multiple parts is to select With Work Piece Zero Points. This is the best choice when parts are being held in multiple vises, or other fixturing means, where they do not share the same piece of stock. Setting this up is also a piece of cake. First, load the program you want to run, and probe the stock in the first location, and set the zero point. Now, you will need to store this to memory: under Work Piece Setup, go to the Work Piece Management and add a new position to memory:

Then, populate some information about the new position you want to add, and at the bottom, click Save:

Next, to store your current zero point to memory, return to the Work Piece Management menu, select the position you just created, and select Overwrite.

Perform this task for each piece of stock that you want to mill. Once this is done, return to the Execution Options menu. From here, select With Work Piece Zero Points under Layout, then click Add Zero Points.

Then select all the positions from before and click Save.

Now your positions are selected, you can reorder them, or add more positions. Otherwise, click OK. Then simulate to verify the operation.

You can even further optimize the process by choosing Optimize Tool Change under Execution Options menu. This will use the tool in the spindle across all parts before changing to the next, thus reducing time spent changing tools.

And that’s about it – now you can batch mill parts easier than ever, without all the fuss on the front end.

Download Free Batch Production Case Study (real-world example):

How Batch Production Improves Manufacturing Efficiency and Reduces Costs

Batch Production or batch machining for lights out manufacturing of of anodized aluminum front panels for use in the electronics industry.

If you think of batch production as an endless shift of “part in, part out” you’re not alone. Certainly, machine operators responsible for loading blanks, machining them, and removing the finished part – over and over repeatedly – share the view that a shift can be mundane and at times even seem endless.

But, with the right equipment, batch production or batch machining can be cost saving for the manufacturer and liberating for the machine operator. Further, if planned carefully, batch production strategies can facilitate unattended production or lights out manufacturing which add to the cost savings realized by manufacturers.

Batch machining or unattended lights out manufacturing using large format DATRON high speed milling machines with integrated vacuum table workholding to hold sheet material during milling.
Batch machining using vacuum chuck to hold sheet material.

The Batch Production “Ideal”

Using milling machines with large beds reduces operator intervention since they accommodate numerous or sizable “blanks” that can yield a full batch in a cycle time that coincides with the length of an operator’s shift. That way, the operator can place a batch on the machine in the morning and attend to other duties during the day. The automated machine works all day producing the needed pieces. Near the end of the shift, the operator removes the completed batch, sweeps down the machine, and sets up another batch to run unattended all night.

When the operator returns to work the next morning, he removes the batch that the machine produced overnight and starts up another one. This gets two shifts’ worth of work out of a single operator. This is the principle of “lights out” production — so named because the machine is left running overnight when everyone has gone home. Of course, this scenario reflects the batch machining “ideal”, since it keeps the machine operating unattended for most of the workday and at night. This may not fit your exact application but, the closer you can get to this ideal, the more efficient and cost-effective your operation will become.

Note: Achieving the highest degree of efficiency or the “ideal”, requires increasing the machine’s role in the process while decreasing the need for operator supervision. So, manufacturers striving to reach this ideal must employ the right machines and also identify alternative labor functions to fill the void left by the operator’s diminished role in production.

Unattended / Lights Out Production in Theory

Based on an 8-hour day, let’s say labor costs about $0.40 a minute and a machine costs about $0.20 a minute to operate. So, if you tie an operator to the machine with one-up production, your total cost will be $0.60 a minute. If you were to run two shifts, the machine would cost only $0.10 a minute, while the labor cost remains the same at $0.40 a minute. Although it’s a savings, it falls short of maximizing the impact on a manufacturer’s bottom line … and more can actually be saved. By setting up a machine to do the work without operator intervention during the second shift, the reduction in the labor cost brings the machine cost as low as $0.05 a minute.

While the cost of labor is something that the manufacturer cannot control, companies can still achieve substantial savings through batch machining that gets twice the production from a single operator with no increase in labor cost. This method can be expanded into “lights-out” production (one shift of unattended machining) to further reduce machine costs. Any form of batch machining is superior to one-up production and represents a “set it and forget it” method to achieve cost-effective, efficiency with machines that were designed to be automated in the first place. A machining center featuring a large working area (bed) and possibly automation offers a complete solution for batch machining that will directly and positively impact a manufacturer’s bottom line.

Download Free Batch Production Case Study (real-world example):