TrewFit Controls design and manufacture class-leading products for the valve and automation industry | Metalworking News

As Industry 4.0 initiatives bring more and more industrial axes of motion into the realm of automation, the need for cost-effective control across them grows as well. Advances in robotics, connectivity, cloud computing, artificial intelligence, data analysis, mobility, and numerous other areas are converging to push global industry to new plateaus of operational efficiency and creating roles for automated actuators in places previously thought impractical.

Playing an important role in this era of control and controlling costs is Trewfit Controls, a Benrose, Johannesburg-based manufacturer of a full range of limit and proximity switches and switchboxes for use on all pneumatic actuators.

“TrewFit Controls design and manufacture products for the valve and automation industry. As registered patent holders we take pride in the fact that products manufactured by the company are the result of the company’s own research and development. The company has gained its knowledge from sound participation in the markets in which its products are deployed,” explains Director Roy Clague, who informally looks after the manufacturing side of the business.

TrewFit Controls manufacture a full range of limit and proximity switches and switchboxes for use on all pneumatic actuators

“In the world of automation and mechanical engineering, actuators play a pivotal role in translating control signals into physical movement. Among the various types of actuators available, pneumatic actuators stand out for their efficiency, reliability, and simplicity. Designed to harness the power of compressed air to generate motion, these devices are integral to a wide range of applications, from industrial machinery to robotics, and even in aerospace technology.”

“The actuators where our products are used are with are the ones linked to valves, both rotary and linear, which are used in any industry that requires a recipe for mixing materials, from food and pharmaceuticals to slurry and refuse and everything in-between.”

An example of a TrewFit switchbox

“Enabling actuators to play a central role in Industry 4.0 initiatives has been the integration of microelectronics into what were previously mechanical systems. The use of just a few wires to connect power sources and networks improves actuator controllability and design flexibility for machine builders, while simplifying installation, diagnostics, and maintenance for end users. These factors combine to enable automation on previously manually operated axes, which can contribute to increased efficiencies in plants, vehicles, and buildings. The most important benefits a design engineer can expect from this new generation of smart actuators include low-level power switching (plc compatible), dynamic braking, end-of-stroke indication, improved position feedback condition monitoring and real-time communications.”

What is a pneumatic actuator?“A pneumatic actuator is a device used to convert energy, specifically compressed air, into mechanical motion. At its core, the principle of operation is fairly straightforward. The actuator uses the energy derived from the compressed air to move a piston within a cylinder, which in turn generates motion. This motion can be linear or rotary, depending on the type of actuator being used. Linear actuators move objects in a straight line, whereas rotary actuators impart circular motion. The simplicity of air as the driving force makes pneumatic actuators highly reliable and efficient, offering significant advantages in terms of cost, maintenance, and safety.”

Plastic switchboxes with 2 x proximity sensors fitted onto manual ball and butterfly valves

“These devices are composed of several key components including the cylinder, which houses the piston and the compressed air; valves, which control the flow of air into and out of the cylinder; and the piston itself, which moves in response to changes in air pressure. This setup allows for precise control over the movement, speed, and force of the actuator, making it an invaluable tool in a vast array of applications. From the automation of industrial machinery to the precise control required in robotics and the robust demands of aerospace technology, pneumatic actuators are a critical component in systems where reliability and efficiency are paramount. Their capacity to operate in hazardous environments, where electrical sparks pose a risk of explosion, further broadens their applicability across industries, underscoring their versatility and importance in modern engineering and automation solutions.”

“Limit switch boxes enhance safety by monitoring actuator positions to prevent accidents, improving efficiency by enabling precise control, and extending equipment longevity. They are engineered to withstand diverse operating environments thanks to their durable construction and compatibility with various temperatures and explosive atmospheres.”

“Choosing the right pneumatic actuator is a critical decision that hinges on understanding the specific requirements of your application. Key factors to consider include the type of motion needed (linear or rotary), the force required to perform the task, and the speed at which the actuator must operate. It’s essential to evaluate the load the actuator will need to move, as this will directly influence the size and type of actuator required. Environmental conditions, such as temperature extremes, presence of corrosive substances, or potential exposure to water and dust, also play a crucial role in selecting an actuator designed to withstand these challenges. Additionally, the precision of movement and repeatability may be vital for tasks demanding high levels of accuracy. Pneumatic actuators come with various customisation options, including adjustable cushions, stroke lengths, and mounting configurations, allowing them to be tailored to meet the nuances of different applications.”

“Understanding the air supply available in your facility is equally important, as it affects the actuator’s performance and efficiency. By meticulously assessing these factors, you can ensure the selection of a pneumatic actuator that not only aligns with your operational needs but also enhances productivity and reliability in your processes.”

TrewFit Controls have 5 CNC machines so they can offer custom machining and manufacturing as well as engineering work requiring precision CNC milling and precision CNC turning over and above the company’s own requirements

“Our core products revolve around the monitoring and controlling of valves and actuators used in various industries across South Africa. We offer a full range of limit and proximity switches and switchboxes for use on all pneumatic actuators.”

“Limit switch boxes enhance safety by monitoring actuator positions to prevent accidents, improving efficiency by enabling precise control, and extending equipment longevity. They are engineered to withstand diverse operating environments thanks to their durable construction and compatibility with various temperatures and explosive atmospheres.”

“Safety: They make operations safer by monitoring the position of the actuator. If the actuator moves too far or not far enough, the limit switch box can detect this and help prevent accidents or damage to equipment.”

“Efficiency: These boxes help actuators work more precisely, reducing mistakes and the need for redoing tasks. This means processes can run smoother and faster, saving time and money.”

TrewFit Controls regard themselves as a part-time jobbing shop on the machining side. They don’t offer large production machining services but can do limited runs

“Longevity: With proper maintenance, limit switch boxes can last a long time, often 10 to 15 years. This makes them a reliable part of the system, contributing to the overall durability of the equipment they are used with.”

“The switch boxes go on top of an actuator, generally a pneumatic actuator, and the actuator will drive a valve. Through its drive mechanism on the bottom the switch indicates if the valve is open or closed. The switch box is a multifunctional unit that gives panoramic visual indication of the valve position as well as an electrical feedback from two micro switches. The terminal strip and twin conduit entry points allow a solenoid valve and micro switches to be wired up through a single multi core cable.”

“They come standard with either a plastic or aluminium mounting kit. The switch box is mounted with plastic or aluminium to the actuator with a standard Namur mount, and the actuator is mounted to the valve with stainless steel brackets that vary according to the valve.”

The TrewFit product range includes valve positioners, valve position indicators, several service proximity switches and mounting accessories for various valves and actuators

“These days all limit and proximity switches and switchboxes can be remotely monitored and some are remotely controlled. We have our own PC boards to do the data transmission. Basically, the bases and housings manufactured in either aluminium or plastic are the same but the PC board components and switch configurations differentiate the individual products. They also depend on what the client wants, whether they are high-tech or not. Some even want their own colour coating and company logo.”

“We manufacture a multitude of variants, depending on what the client wants. The bases for the switches are made in either plastic, which we have moulded locally, or in aluminium. The aluminium bases are high-pressure die cast in China and not manufactured in China. All the machining and assembly gets done in our factories. We would like to have them manufactured locally but until we can find a high-pressure die cast foundry that supplies us product without porosity, only then will we re-shore.”

“We used to manufacture the plastic bases abroad. The injection moulding tools were made in China so we got the bases made there as well. But we ended that endeavour because of the cost. It was cheaper to have them manufactured in China but the freight costs have gotten out of hand. It’s now cheaper to produce it locally.”

TrewFit Controls’ have a full CNC engineering facility that offers CNC turning services of different materials

“We also manufacture high-temperature versions, product that will withstand 400 degrees C for two hours.”

“We are exporting to Europe, the East and some into America. We’re really trying hard there, but it’s a difficult market to penetrate.”

“The Trewfit product range includes valve positioners, valve position indicators, several service proximity switches and mounting accessories for various valves and actuators.”

“As far as we know we are the only company that manufactures these components in South Africa. All other products are imported. When you look at the South African market for the use of actuators, valves and automation it is valued in the billions. There are opportunities but manufacturing locally does give us an advantage.”

“I joined the company a couple of years after it was established in 2009, by brothers Adrian and Bruce Penning. The company manufactured valve controls, locally, for an international company.”

The machine shop is housed in a 700 square metre building, completely separate from assembly, so as not to have any contamination

“Bruce then decided to go live and work in America and offered to sell his share in the business to me. At the time I worked for Fanuc South Africa selling the RoboDrills, robots and Robocuts and had been calling on the company. After 13 years with Fanuc, I was looking for a new direction and I accepted Bruce’s offer. I have known Adrian since high school days, although we attended different schools.”

“I was quite knowledgeable in CNC machining, because of my background. I had sold them a couple of RoboDrills so I would easily be able to pick up the manufacturing aspect and run with it. I was grateful that I was offered the opportunity to take a shareholding in the company.”

“About 6 months later the international company that we did all the work for decided to move all manufacturing to China. Adrian and I decided to design and manufacture our own switch box locally. We found two local investors who had an interest in the local valve market and we went forward from there.”

“We did not have any clients but we had the contacts. Thankfully the base has continued to grow over the years.”

The company has three Fanuc RoboDrills

Custom manufacturing and CNC work“As I said previously, we buy in our castings and have the injection moulding done locally. We do not machine from block as it is too complicated and the numbers do not make sense. But we do have 5 CNC machines so we can offer custom machining and manufacturing as well as engineering work requiring precision CNC milling and precision CNC turning.”

“On the software side we have the latest design and machining package so we are able to offer these services. We regard ourselves as a part-time jobbing shop on the machining side. We certainly don’t offer large production machining services but can do limited runs.”

Partners Roy Clague and Adrian Penning

“The client base on this side is very varied but also interesting. Machine shops work in a very complex world these days, as the demands to get product to the customer on time and with the greatest quality is becoming more important every day. Many machine shops struggle to get jobs done on time for various reasons, so it is important to look at how you structure your shops to meet demand and cause the least amount of stress in the shop and keep sanity in the shop.”

“The machine shop is housed in this 700 square metre building and we have a duplicate building across the car park that houses assembly. It is important that we keep the two apart because a machine shop can cause a fair bit of contamination.”

“What we did not realise though when we rented the property is that the council authorities regard the two buildings as separate entities. As a result the electricity bills are challenging. Johannesburg electricity costs are high.”

Core offerings focus on the monitoring and control of valves used across sectors such as mining, manufacturing and food and beverage production

“We have IECEX, ATEX and SANAS certification for our hazardous area products. We are also a certified manufacturer under these standards. We also manufacture AS-i certified products. We distribute DigiTrak smart positioners as well as Neuma pneumatic products and MaxAir composite pneumatic actuators.”

“We have a staff complement of 24 at the moment.”

For further details contact TrewFit Controls on TEL: 011 614 8073 or visit https://trewfitcontrols.com/about-trewfit-controls