Marnic Precision Engineering

Because Marnic Precision Engineering machines a large portion of its precision-machined components for the aerospace and defence industries, which require tight tolerances, the word precision in the company name is a pre-requisite. It might also service clients in the medical, mining, power and energy, automotive, food and beverage, petrochemical and agriculture industries, but to a lesser extent. Prevailing circumstances in the aerospace and defence industries could see the company give more attention to these other industries though.

Christa and Pottie Potgieter of Marnic Precision Engineering, who together established the company in 1989

Marnic Precision Engineering is a machine shop that has successfully served aerospace customers for over 25 years. In fact, this market represents a large percentage of the work that currently flows through the Benoni, Gauteng business.

That said, it is becoming more challenging to serve that industry because of the turmoil in an industry that is dominated by the state-owned enterprise Denel, explained Martin Potgieter, a Director at Marnic Precision Engineering.

“Many South African aerospace companies are single source suppliers of components and assemblies to the likes of Saab, Boeing and Airbus to name a few. In addition, South Africa also has a long track record of producing full aircraft and complex aircraft systems from for instance the Rooivalk helicopter all the way to general aviation aircraft such as the Sling, to building aircraft under licence, such as the Dassault Mirage. South Africa also has a very mature research and development agenda through which the country has become a globally recognised leader in key technological offerings such as titanium beneficiation, air traffic management, avionics and electronic warfare systems and UAV’s, to name a few.”

Amongst the milling machines that Marnic Precision Engineering has are four Quaser MV 204 II vertical machining centers

The heart-beat of the temperature-controlled measuring capabilities are a Mitutoyo Euro-C-A9106 and a Wenzel LH 54, which is equipped with a Renishaw Revo probe system to give the company 5-axis measuring capabilities

“Relatively speaking the industry in South Africa is not huge, but is at the same time demanding. The Denel companies that serve the industry have been under pressure to make money because overall the Denel Group has been draining state resources. Denel Aerostructures is one area that the new management that was appointed in 2019 has now decided to exit and wind up. The aerostructure manufacturing business was just no longer sustainable for Denel, according to Denel’s media releases.”

“This has a knock-on effect to many of the Aerostructures’ suppliers, first, second and third-tier. The positive out of this recent announcement is that Denel has reached an agreement with its customers to transfer the manufacturing of aircraft parts and components to alternative suppliers. Hopefully those alternative suppliers are South African companies. Fortunately, we are not really exposed to this development but it is an example of the turmoil in the industry.”

“It is sad to see especially after all the announcements in previous years about Aerostructures’ big work packages from global manufacturers that it was involved in and was negotiating for.”

At the moment aluminium machining makes up 70% of Marnic Precision Engineering’s material usage

Marnic Precision Engineering has recently introduced semi-automatic welding

Marnic Precision Engineering was established in 1989 by Pottie Potgieter. The business has grown from the backroom of the Potgieter’s family home to the current facility in Van Wyk Road, Brentwood Park, Benoni. In between the company occupied two factories in Howard Avenue in Benoni for 20-odd years before it became too small for the company’s needs. This also coincided with Marnic Precision Engineering winning big contracts to supply non-conflict components for the defence industry in South Africa and internationally.

Prior to starting Marnic Precision Engineering in 1979, at the age of 26 Potgieter purchased a conventional lathe, which he installed at his home and worked on it in his spare time to earn extra revenue. Two years later he was able to afford to purchase a second machine and this time it was a Bridgeport milling machine, which is still operational today.

Potgieter’s extra mural machining activities were formalised in 1985 when he registered a company PM Engineering. Due to the growth of the operation he had to move from the backyard room to a 250m² factory, which he would later purchase, in 1989. At the same time he registered Marnic Precision Engineering and took on a partner. Two years later Potgieter purchased his partner’s shares and became the sole member.

A component being produced on one of the Wire EDM machines

Marnic Precision Engineering manufacture components for the aerospace and defence industries

By 1994 Marnic Precision Engineering’s staff had grown to 16 and the following year Potgieter purchased the 400m² factory next door and soon filled it with machines after purchasing a machining operation that had gone into liquidation. The increased capacity would open new doors for Marnic Precision Engineering. 1995 continued to be a good year for Marnic Precision Engineering as one of the new clients that the company acquired would become the company’s biggest client. The client is a globally leading defence and security electronics provider, based in Germany. This company has two South African manufacturing sites, both of them being their biggest manufacturing sites outside of Europe. This client is still a loyal client today.

Marnic Precision Engineering would continue to grow and in 2003 acquired Jawo Engineering, a manufacturer of precision components for the aircraft and defence industries. As a result of the purchase Marnic Precision Engineering would also acquire CNC machines and more conventional machines.

Changing of the guard
The family run business began its potential handover to junior members of the Potgieter family in 2006 when elder son Jacques Potgieter (37) joined the company. It took some time before younger son Martin (36) also joined the family business. Martin studied Mechanical Engineering at Tukkies University before spending a number of years in the design department of a communication and information technologies company. It was there that he became familiar with ProEngineer design software and when he decided to join the family business in 2015 he was able to bring a new dimension to the company, namely a design department.

A specialist product that Marnic Precision Engineering manufactures is for the diamond sorting industry

All cutting tooling inventory is controlled by Iscar’s Matrix vendor

“The move to our new facility in Brentwood Park five years ago was traumatic but also exhilarating. We built our 2 400m² factory from scratch, a greenfield opportunity that allowed us to design and construct the building as we wanted the layout to be. You could say we have two distinct bays now – one housing our conventional and Wire EDM machines and the other all our CNC equipment,” explained Martin Potgieter.

“A separate building houses our semi-automated welding department, which we only commenced with in 2019. The extra building was constructed originally to rent out but with our expansion into welding it does not look like that is going to happen.”

CNC milling capabilities
“We now have a total of 25 CNC machines. On the milling side we have 18 machines and we can process workpieces up to 2 000mm by 1 000mm by 800mm. Besides normal milling processes our machines are doing thread cutting, tapping and complex surfacing with a bore roundness accuracy of five micron and a positioning accuracy of 10 micron.”

In the CNC milling department Marnic Precision Engineering has a Doosan DNM 650 vertical machining center, supplied by Puma Machine Tools

The company has three Fanuc RoboDrills. All three are the Fanuc α-D14liA5 series

“The last time we purchased new equipment for the CNC department was in 2017 when we purchased a Doosan DNM 650 vertical machining center with XYZ travels of 1 270mm by 670mm by 625mm, a 22.4kW motor with 8 000rpm.”

“That same year we also purchased three Fanuc RoboDrills. All three are the Fanuc α-D14liA5 series, which are compact machining centers with XYZ travels of 700mm by 400mm by 330mm, a working table space of 850mm by 410mm and a table load of 300kg.”

“Other milling machines that we have include four Quaser MV 204 II vertical machining centers and a DMG MORI DMU 70 eVolution, which is a 5-axis simultaneous machining center with XYZ travels of 750mm by 600mm by 520mm and a table weight of 350kg. The CNC Quasers have XYZ travels of
1 020mm by 600mm by 560mm and a table weight of 1 000kg.”

“We also have two Johnford VMC 850 vertical machining centers at our disposal.”

CNC turning capabilities
“We do not have as many CNC turning machines as compared to the CNC milling machines. Even so we are well catered for with seven machines of various specifications. We can process workpieces with an OD of up to 550mm, a swing of 500mm and between centres, a length of 1 500mm. Bore roundness accuracies are five micron and concentricity 10 micron.”

“Among the CNC lathes we have a Mazak Quickturn Nexus 200 and an Okuma 270E.”

“On the conventional turning machines side we can accommodate work pieces of up to 650mm OD and 2 500mm between centres.”

“We have five machines in our EDM wire cutting department and here we can accommodate workpieces up to 300mm.”

“Other capabilities of material removal or processing include surface and cylindrical grinding with accuracies of two micron and then we also have conventional milling.”

“In total we have 40 machines setup between the CNC bay and the conventional bay.”

Among the CNC lathes that the company has is a Mazak Quickturn Nexus 200 and an Okuma 270E

Components manufactured by Marnic Precision Engineering

“With all this type of equipment you would think that we are a mould and die manufacturing shop but we certainly are not. We have the capabilities but in the history of the company we have not made any moulds for injection moulding, for example. Our business is about precision components with tight tolerances. Additionally, we do not process long runs of the same component like a production shop.”

“However, we do run small batch production runs when required to.”

Temperature-controlled inspection
“With the types of industries that we manufacture components for, which are shipped directly to the assembly line, our clients expect first-time quality from us. There are no incoming quality checks or receiving inspection routines. The onus is on Marnic Precision Engineering to get it right first time, all the time. They simply rely on us.”

“Temperature is the single largest source of measurement error. Control it, and your CMM or gauge should meet all performance criteria. Dimensional control is an important part of manufacturing, yet those trying to achieve precision measurements often forget the single largest source of measurement error: Temperature.”

The company has two Johnford VMC 850 vertical machining centers in the milling department, supplied by Skok Machine Tools

An aluminium component manufactured by Marnic Precision Engineering

“In most shops, temperatures change over time and space. One part of the shop might be warmer or colder than another, and the temperatures within different areas can even change at different times of the day. As temperatures change, so will the measured values of critical dimensions. And as manufacturing tolerances get tighter, it’s not only important to consider your machine or gauge’s ability to resolve to smaller values, but also how temperature may affect your measurement results.”

“Information gleaned from the inspection department is distributed to the machine tool operators and they act or make adjustments accordingly. Therefore, it is even more critical that your inspection results are correct. The machining process employs the power of accurate dimensional data to provide true process control.”

Brothers Jacques and Martin Potgieter in front of the DMG MORI DMU 70 eVolution, which is a 5-axis simultaneous machining center

Another component that Marnic Precision Engineering has manufactured

“For this reason, when we built this building in 2015, we made provision for a centrally located temperature-controlled inspection room. Various micrometers, height gauges, optical comparators and hardness testers are housed in this room but the heart-beat of it are our two CMMs.”

“The one is a Mitutoyo Euro-C-A9106 and the other is a Wenzel LH 54, which is equipped with a Renishaw Revo probe system to give us 5-axis capabilities.”

Reverse engineering
“We have the capabilities to reverse engineer components and assemblies. We can provide prototypes for clients, with all the testing and analysing done, before production begins. The steps followed usually consist of analysing the component function, measurement and material analysis, 3D modelling with Mastercam, manufacturing followed by measurement, testing and verification.”

“We are also able to carry out stress analysis and finite element analysis tests.”

“Other normal fabricating, finishing and assembly services are also offered.”

Marnic Precision Engineering don’t just machine one-offs. They have stock on the shelf for clients

Some more aluminium components that Marnic Precision Engineering has manufactured

“We do process most materials. At the moment aluminium machining makes up 70% of our material usage. Additionally, we will not just make one component and supply. We rather make a few of the same component and hold them in stock so the client is not kept waiting when he next orders. The numbers vary because of the specialised types of products we manufacture or the components that we machine.”

“Currently Dad is handing over to Jacques and myself. He is reducing his involvement but we still rely on his advice heavily. From his small one-man one machine shop the company has grown to 35 staff, with 29 on the shopfloor, offering a multitude of high-tech services. Something that we are very proud of and we intend to emulate him so that he looks at us proudly.”

“You can never be happy with the equipment that you have on your floor. Even though we have 5-axis machining and CMM inspection, we don’t have live tooling yet or additive manufacturing capabilities. It is something for the future. As is digitalisation and the move to integrated, data-driven manufacturing.”

For further details contact Marnic Precision Engineering on TEL: 011 421 7832 or visit