It is generally accepted that most UK machine shops typically achieve overall equipment effectiveness (OEE) values of 50% or less. However, most will want to decrease downtime and make their CNC machine tools as efficient as possible. Less downtime equals more productivity, which means increased profitability.

Whilst fully automated machine shops might be achieving upwards of 90% OEE, these are rare examples and there are still tons of opportunities to boost your OEE if you’re not planning on going fully automated any time soon.

Guided by our Technology Centre Manager Kasra Mehraky, in this article we’ll outline how you can improve your machining OEE by implementing a few timesaving, cost-cutting and productivity-boosting technologies.

Factory automation is no longer limited to high-volume production environments. Robotics can substantially reduce overhead costs and improve competitiveness in pricing.

Many examples of automation include reducing elements of human error and human intervention in the process.

The simplest example of automation within the machining process is machine tending.

“Instead of having an operator taking a part out, putting a new one in and pressing cycle start, you can have a robot doing the same with minimal downtime. 

Also, seamless communication between different systems in a machine shop can improve efficiency. For example, sending the tool measurement values from a pre-setter to a CNC machine tool automatically can streamline the process and prevent human errors” says Kasra.

Experienced machinists will tell you that measuring parts with the machine that made them is asking for trouble.

And while that might be true for extremely close tolerance work, today’s machine tools and probing systems can easily measure features to within four to five microns, increasing accuracy and reliability.

Renishaw, partners of MSC Industrial Supply Co. UK, are the industry leaders in making these probes.

• Renishaw provides spindle probes for part set-up and verification
• Renishaw also provides tool probes which can measure the length and diameter of a tool inside the machine, as well as monitoring tool wear and potential breakage
• And finally, Renishaw provides shopfloor gauging and measuring systems such as Equator and Equator-X

Kasra explains: 

“Return on investment with probing can be extremely quick. You may spend a few thousands of pounds on a probe, but the amount of scrap parts that you save means that it pays back for itself in no time.

“Systems such as Equator can also be integrated in an automated way. For example, part of the duty of a robot when taking a part out is to put it on the Equator, the Equator then measures it, and it makes sure that it is machined to the right tolerances. 

"If it is off by some amount, it can send that data to the machine tool and the machine tool knows that it needs to rework that part instead of scrapping it, or it could adjust the tool offsets for the next part. This creates an end-to-end closed loop process, fully automated.”

When putting a cutting tool into a machine, we need to know the diameter and the length of it and ensure it is measured accurately.

To do this, you could:

• Take a pair of verniers or callipers and measure it manually, which is quite inaccurate.
• Put the cutting tool inside the machine and use the machine plus a few tools - such as a Z-axis setting indicator - to measure it.

“Both of the above examples are time consuming. Your machine needs to be cutting to make money, so you don't want to waste that time with the tool set-up, which is where an offline tool pre-setter could help.

“A tool pre-setter is a device that measures the diameter and the length of the tool outside of the CNC machine.

“You can send this data from the tool pre-setter automatically to the machine tool, avoiding the risk of manual error of input and the tool crashing into the part.

“There are also RFID tags inside some of the new tool holders that ensure you are putting the tool in the correct pocket inside the magazine. Even if you misplace it in the pocket, the machine knows which tool it is and it already has the data for the length and the diameter from the tool pre-setter” Kasra adds.

Commonly many machine shops might not know what tools they have on the shelf, or what condition they are in. They might get a new job through the door and simply order more tooling for it, not knowing they already have something that can do that job for them on the shelf.

“We've got software packages that can help with this: tracking the conditions of the tools the company has in stock and what condition they are in. This saves cost, removing duplicate ordering and time waiting for new tooling to arrive” Kasra adds.

The opportunities for OEE improvement with quick-change tooling are endless.

Kasra comments: “For machining centres and EDM equipment, zero-point work holding systems turn job changeover into a one-minute-or-less affair. 

“The same can be said for quick-change chucks and top jaws on a CNC lathe. On the cutting tool side, quick-change tools and live toolholders not only reduce machine downtime but also eliminate the hassle of bending over to inspect tools or digging in the chip conveyor for dropped screws and inserts. Pop the worn tool out, stick a new one in and press cycle start."

With Toolpath simulation software, you upload a program to the machine, push the green button and walk away. What Toolpath simulation software can do is prevent machine crashes - the worst thing can happen for a for a machine tool. This is particularly relevant if you are doing 5-axis milling work or multi-spindle multi-turret turning.

It can also help to identify which method of machining is the most efficient. Every programmer machines differently, by simulating the tool path you can identify which method would be quicker, more efficient or would be most effective at increasing tool life.

Kasra explains: “At MSC’s UK Tech Centre, we use simulation software. In fact, it's in our policy, so we cannot send any NC programs directly to the machine without first proving it on the simulation software.

“If you are doing a lot of one-off jobs - like what we do here at MSC often - having a capable toolpath simulation software makes life a lot easier. 

"Using a software to check for potential collisions and errors is lot less stressful than having both of your hands on the feed controls whenever you are proving out a new job.

“And for longer-running jobs, such as more than a few dozen pieces, these software systems give programmers the ability to fine-tune toolpaths and drastically shorten cycle times."