CNC Machines: Routine Maintenance is Necessary to Avoid Costly Downtimes

The increased use of computer numerical control (CNC) machines in glass production allows for more efficiency, improved productivity and safer work environments. Regular maintenance is essential to keep these machines working at their best. This comes in the form of weekly, monthly, quarterly and semi-annual inspections.

CNC machines are often used to cut, carve and form parts based on a computer code that controls the machine’s movement and speed. The machine does this autonomously and without any human intervention once the manufacturing code is generated. CNC operators run and monitor the machines, while CNC programmers create and run the codes.

A CNC machine needs routine maintenance to perform optimally. This includes cleaning, lubricating and monitoring changes in performance. A maintenance schedule is also based on the machine itself.

“I would say 75% of maintaining the CNC is cleaning and inspecting,” says Jason Berlin, technical support manager for Oldcastle BuildingEnvelope®, a provider of architectural glass products based in Dallas. “The rest is training maintenance and the operator to listen to what the machine is telling you.”

Viracon process engineer Adam VanderStelt says that CNC machines need daily, weekly and monthly maintenance to work as intended. To do that, the Owatonna, Minn.,- based architectural glass fabricator implements a 5S program (sort, straighten, shine, standardize and sustain) to maintain its machinery. It also cleans and lubricates the axis motors, bearings, ways and removes grindings from the coolant systems.

Additionally, Viracon uses total productive maintenance programs that include monitoring axis play and spindle runout. The company’s maintenance technicians also replace consumables and durable components that wear over time for machines such as its LiSEC KBF, which is a glass edge grinding machine that edges all four sides automatically.

The constant maintenance allows engineers to track changes in performance and longevity, which “provides an early indication of possible upcoming maintenance concerns,” says VanderStelt.

To ensure that CNC machines run smoothly, operators and maintenance teams need to work hand-in-hand to keep downtimes at a minimum. That’s because downtime is the most expensive aspect of owning a CNC machine, says Berlin. “The cost of poorly maintained and operated equipment can lead to unplanned downtime costs, labor costs and costs of poor quality,” says Doug Zirngible, Viracon’s director of engineering. “With the added challenges of parts availability leading to even longer downtime potential, it’s even more critical to make sure the equipment is running at top performance and the staffs are highly trained.”

Operators and maintenance technicians need to be trained to collaborate as one team to document the day-to-day processes even through shift and staffing changes. Training employees to remain up-to-date with operating manuals and updates is difficult, says Berlin. He adds that his company keeps a comprehensive schedule to maintain training.

Tim Greene is a product engineer for Isoclima Specialty Glass, a Selma, Ala.,-based company that provides high-performance specialty glass. He agrees that training an employee to operate a CNC machine can be tough. A CNC operator faces a high learning curve. Job requirements include preventative maintenance, troubleshooting, understanding G-code programming or Cartesian coordinate systems, reading blueprints and installing required fixturing, among others.

“If you require your operator to program or write code, it’s very difficult,” says Greene. “Generally, we have software to create the CNC toolpath or have a few dedicated personnel that can create programs and tool paths. This will allow an operator to load material and just execute a program or file. It is extremely difficult and costly to train an operator on handling CNC programming. A machine could run itself out of bounds, it could run itself into another tool or part and cause high dollar damage if the program is not correct. Generally, this is not done by our general labor.”

A CNC machine is a vital component of modern manufacturing processes. It enhances production efficiency and allows smallscale manufacturing to be achieved with high injection rates at low cost. Without proper maintenance, however, a CNC machine is just another hunk of metal taking up space.

“A complex machine that is operated poorly can create issues even if the maintenance is done regularly,” says Franco Ortiz, Viracon maintenance supervisor.

Joshua Huff is the assistant editor of USGlass magazine. Email him at and connect with him on LinkedIn.

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