The South African aluminum diecaster invested in its facilities, and it paid off with increased orders from automotive OEMs.
Bruce Crawford, Castings SA, and Global Casting Staff
Facing pressure to cut carbon emissions and increase fuel efficiency, the automotive industry is demanding highly integrated, lighter components without diminished mechanical properties. This trend offers aluminum diecasters the opportunity to create complex components that fulfill several functions while reducing weight and improving efficiency.
Zealous Automotive, part of the Zealous Group, Springs, South Africa, along with a pressure casting division, invested heavily in its aluminum diecasting operation in 2007. That foresight resulted in a 2012 deal with Volkswagen of South Africa that included an order of 130,000 cam carriers, each weighing 5.3 lbs. (2.4 kg), for the four-cylinder, 1.4-liter Polo engine.
“To succeed with a project of this enormity and importance, you have to invest in the latest technology available,” said Graham Hardisty, Zealous COO. “To this extent, we have invested more than 61 million rand [$6.23 million] in the plant and equipment and [continue] to explore opportunities to supply the automotive OEMs.”
He believes South Africa has the expertise to be a reliable supplier of aluminum castings and compete for large international contracts.
“Planning [for facility upgrades] started in 2007 and equipment was only ordered in 2010.The first samples came off the line in May 2011, and these were only approved in January 2012. Start of production took place that March and will operate in three shifts,24 hours a day, five days a week.”
Zealous has concentrated mainly on zinc castings since it was established in 1970. The privately owned company has refocused its efforts in recent years.After completely divesting aluminum in 1980 to focus on zinc, Zealous re-entered the aluminum diecasting industry in 1996. Aluminum accounts for 70% of its current daily production of approximately 6 tons. More than 5 tons of castings are shipped daily.
The Zealous Group split into two main divisions in 2003, when it formed Zealous Automotive to accompany its pressure casting business. In 2009, Zealous reached an agreement with Ukuvula Investment Holdings, Port Elizabeth, South Africa, a firm with roughly half its portfolio in the automotive industry. It acquired a 26% share of Zealous holdings.
Zealous Pressure Castings specializes in non-automotive products and utilizes a more traditional approach to diecasting in zinc and aluminum. The zinc department currently has 13 hot and cold chamber machines in operation ranging from 20 to 500 tons, and the aluminum department currently has 14 machines in operation, ranging from 60 to 700 tons, supported by a 1.5-ton Striko smelter.
“Entering the automotive OEM market in 2001 with a Toyota contract and substantially increasing our footprint in 2004 with Volkswagen’s LT3 engine project, Zealous Automotive was strategically developed and registered in 2003 to fill a niche market in South Africa with a longer term view of export outside Africa,” said Steven Reid, CEO. “There are currently seven diecasting cells within this division capable of running a three-shift system six days a week, supported by a 2-ton/4-ton Striko smelter.”
Nearly a decade into its Volkswagen LT3 project, Zealous has cast a total of nine components with more than 200,000 engines built for export.
“During this time, we have developed a full metallurgical laboratory and a metrology department where we have access to 3-D digital content creation measuring for full in-process inspections and full machining capability on 17 CNCs, making Zealous a leader in supplying fully machined and assembled aluminum components,” Reid said.
Zealous currently supplies 70% of locally produced high pressure castings directly to OEMs, utilizing approximately eight tons of metal to produce 6 tons of castings per day. In addition to Volkswagen and Toyota, major Zealous customers include ZF Lemforder, Pi Shurlok and Robert Bosh (SA).
“Zealous offers our customers a long-term relationship, utilizing world-class technology with industry accepted processes and up-to-date equipment,” Reid said.“This is supported by high-caliber skills, available capacity and a stable supply of quality components at cost competitive prices.
According to Reid, the agreement with Ukuvula paved the way for even bigger growth opportunities.
Investing in Aluminum
In developing its diecasting operation, Zealous emphasized automation throughout the manufacturing process. Still, the expansion resulted in the company hiring 31 more full-time employees.
“The essence of the whole manufacturing process is automation, traceability and quality control,” Hardisty said.“There are only two occasions where manual intervention occurs, and those are necessary visual inspections for identifying porosity and defects that fall outside of the capabilities and parameters of machinery.”
The diecasting cell is built around a fully automated Buhler Carat compact two-platen hydraulic locking diecasting system.
“The machine is the first of its kind in South Africa,” said Gary Coull, technical manager. “The squeeze pin technology allows us to cast the two center journals solid, something that is essential to the integrity of the casting.”
Trial pre-shot operations are carried out until both the die and metal are the correct temperature to eliminate stresses and porosity before the next operation. A 2-ton Striko dosing furnace supplies aluminum to the diecasting system. Quality checks are installed throughout the process to avoid unnecessary operations on castings that will be scrapped. Zealous engineers refer to this as “process security.”
“The casting cell is controlled by a centrally located ABB robot that extracts the component from the [diecasting machine] before pausing in front of sensors that check the casting’s completeness,” Coull said. “The robot then moves the casting to a quench tank, followed by a positioning on the cut-off saw for removing the runners and overflow. It then moves the casting to a flatness jig that checks for broken cores and distortion.”
Complete castings move to a Borries marking system that inscribes a dot matrix that includes a part number, date, time and unique consequential number. This marking ensures the component will be traceable throughout the manufacturing process and in the field. Castings then enter to a clipping press that removes excess flash and trims the cored holes. The ABB robot places castings on an automatic inlet conveyor.
The casting then is removed from the inlet conveyor by another robot which rotates the casting and places it in a vertical machining center that machines the solid cast center journals. En route to visual inspection, one in 10 castings undergo a complete X-ray inspection using 17 different orientations.
“Once this operation is completed, the robot removes the casting and transfers it to an outlet conveyor,” Coull said. “Here, the first human visual inspection takes place for defects like cold flow, flaking and porosity in the center journals before the casting is placed on an automatic work-in-process conveyor system that holds 2,400 castings, or approximately two and a half days’ production.”
The castings enter a stainless steel shot-blasting unit to achieve Volkswagen-specified roughness on the casting face. From there, they enter the machining cell, which is housed in a facility where machining and dimensional inspection is conducted in a controlled atmosphere with positive pressure for temperature stability.
The castings are fed into three identical double-pallet horizontal machining centers. Each machine performs the same operations, such as facing and machining of the oil channels, before a robot turns the casting around in a horizontal orientation for machining of the chain and exhaust sides.
Like the casting cell, the robot is centrally situated and moves the castings when an operation or cycle is completed. Synchronization with the machining centers is all pre-programmed, ensuring optimal process performance.After this initial machining, the castings are transferred to a CNC machine that does a rough boring and measuring before completing a fine bore.
Full statistical process controls are carried out in-line throughout the machining process. If dimensions extend beyond tolerances, the machine will stop automatically for potential tool change. Another robot then transfers
the castings to a CNC brushing machine that deburrs the machined faces to a specified roughness. From there, the castings are conveyed to a washing machine.
An in-line auto-inspect system carries out three different checks, ensuring every casting undergoes tests for dimensional cam bores, high pressure oil gallery and cavity pressure. Castings are moved via a gantry system. Again, parameters have been pre-programmed to allow for rejected components to be conveyed to a holding area where management can take corrective action to solve problems.
If all three tests are passed, the casting goes for a second visual inspection and is sent for packing. Each container has full traceability so one can be identified easily if it needs to be quarantined.
“This project has shown that Zealous has become a strategic partner with a major OEM,” Reid said. “The facility that we have installed is world class and able to manufacture complex components. There is no reason why we can’t extend our participation in similar projects in the future.”