in Vol. 20 - September Issue - Year 2019
Automated Blasting Technology For Optimum Preparation Of Fasteners
Two AGTOS hanger-type blast machines of type HT 11-13 for pretreating fasteners (rack goods) prior to Geomet® coating
AGTOS continuous overhead rail shot blast machine type DHT 10-08 for blasting rack goods prior to hot-dip galvanising
AGTOS rubber belt tumble blast machine type MG 0180 during unloading
“You can see by looking at a machine the level of quality that has gone into its manufacture”, says Michèl Jacobi, Head of Production at the Geomet® plant
Thielco Steel Solutions Group is investing in four new rubber belt tumble blast machines for Geomet® corrosion protection of small steel parts.
Based in Reuver (NL), the Thielco Steel Solutions Group specialises in professional surface treatment of both large and small steel components for a variety of industrial applications, including the automotive sector, offshore wind, oil and gas and the building and transport industries. Thielco also produces gratings and steps. The company is regarded today beyond the Netherlands as an expert for surface treatment of steel parts through galvanising (hot-dip, hot-dip centrifugal and mechanical) and powder coating.
Thielco has been the sole licence holder in the Netherlands since 2007 for the Geomet® chromium-free coating technology of N.O.F Metal Coatings Europe s.a.
Geomet® technology is water-based and offers an environmentally friendly alternative to conventional coating or galvanising of smaller metal products. A zinc-aluminium laminated coating is applied to the component in a specially designed fully automated production line. This achieves extremely high corrosion resistance and avoids hydrogen embrittlement.
Companies such as Thielco that have acquired the Geomet® licence are subject to the strictest production and quality control and inspections by the licensor N.O.F., thus ensuring the best-possible corrosion protection today for steel parts from a technical point of view. Thielco also conforms to the international IATF 16949 quality standard for the automotive industry for Geomet® coating of steel parts. Many automobile manufacturers use screws and other small steel parts that are surface treated with Geomet® at Thielco. In addition to automotive applications, Geomet®-coated components are also increasingly used in the transport industry and wind turbines.
Hanger-type blast machines for Geomet® coating of rack goods
"We initially only used the Geomet® process for small parts (bulk material), but the enormous growth in the wind power industry in particular meant that the demand for larger components with a Geomet® coating became ever stronger. This led us to invest in a new production line in 2013 for the coating of rack goods with Geomet®", explains Michèl Jacobi, Head of Production in the Geomet® plant at Thielco. "Rack goods are the name of the game, so-called because the parts to be coated are transported on racks rather than in baskets or similar, as it is the case with small parts".
A new production line for fully automated Geomet® coating of rack goods was designed and implemented together with the plant manufacturer WMV Apparatebau. One of the key processes involved here is blasting. Only a perfectly prepared surface will also result in a perfect coating finish that complies with strict Geomet® requirements. Two AGTOS hanger-type blast machines (type HT 11-13) were selected for the blasting process. Each of these is equipped with two high-performance turbines, each delivering 11 kW of drive power.
The third system (also a type HT 11-13) is used for decoating and cleaning the racks. "We coat the workpieces together with the racks in these production lines. The racks are decoated each time following removal of the finished parts, ensuring that fresh racks are always available", explains Michèl Jacobi.
All three hanger-type blast machines can handle a maximum workpiece height of 1.3 m and width of 1.1 m. The blast machines operate with automatic abrasive volume control (via pre-set value) and have a connection for cartridge filter units.
2015 saw renewed investment in an AGTOS blast machine, but for hot-dip galvanising of rack goods in a second Thielco production plant. This system is a linked continuous overhead rail shot blast machine of type DHT 10-08. One special feature of this coating line is the automated loading and unloading of workpieces on the racks using robots, a system developed by the customer.
Replacement of existing blast machines for Geomet® coating of screws
The largest investment to date was made in 2018 in new blast machines for the Geomet® small parts (bulk material) coating line, which has been in operation since 2007.
"More than 10 years of continuous operation of the existing blast machines from another manufacturer had worn them to an extent where they no longer complied with contemporary quality standards. Costs for continuous maintenance and spare parts were high, making any further use of these machines economically impractical. They simply had to be replaced", explained Michèl Jacobi by way of an explanation for this major investment. "We sought the advice of WMV Apparatebau GmbH, a plant manufacturer with whom we have dealt for many years. Additionally, we also needed to take the specifications of N.O.F., the Geomet® licensor, into consideration when selecting new blast machines. Their recommendation and our own extremely positive experience with previous AGTOS blast machines led us to choose four series-connected AGTOS rubber belt tumble blast machines of type MG 0180".
Robust, durable and maintenance-friendly
AGTOS blast machines are distinguished by a high degree of robustness, a long service life and maintenance-friendliness. The high-performance turbines are designed to ensure extremely low wear, even in the severest of operating conditions. Moreover, they are capable of a high abrasive shot flow rate while requiring the same amount of energy as other turbines. They are extremely efficient as a result. The blasting chamber itself is lined with highly wear-resistant, replaceable manganese and tool steel plates.
AGTOS customers always emphasis the high level of maintenance-friendliness of these blast machines. The entire machine is not only designed for long-term operation, but optimised for maintenance and the replacement of spare and wear parts. For example, AGTOS high-performance turbines are equipped with easily replaceable turbine blades, and the push system means that filter cartridges can be replaced without difficulty in the clean gas area. Other servicing work such as replacement of the rubber belt can also be quickly realised, thanks to a well-designed maintenance system.
The tumbling motion of the continuous rubber belt turns the workpieces to be blasted and exposes them to the abrasive stream for the entire blasting duration. The rubber belt ensures that turning of workpieces is relatively gentle. Maintaining low gap dimensions means that even very small parts can be blasted. Machine loading and unloading is automated at Thielco, involving a feeder and discharge chute.
The turbines used in these rubber belt tumble blast machines each deliver 11 kW of drive power and an abrasive shot flow rate of 162 kg/min at the currently configured speed.
The time factor represented a challenge during installation. Within just 10 days, AGTOS and WMV removed the old blast machines with the assistance of Thielco, followed by complete integration, installation and commissioning of the four new rubber belt tumble blast machines in the existing Geomet® coating line. The rack good line continued normal operation during this time.
Efficient, fully automated Geomet® coating process
As if by magic, baskets with bulk material are cleaned and deoiled, blasted, coated several times with a zinc-aluminium laminated coating, cooled and dried in continuous 4-shift operation. Four rubber belt tumble blast machines are positioned parallel to each other in the production line. The baskets with bulk material are moved to the position required in each case by a transfer unit.
"The minimum requirements for Geomet® are two layers of base coat. We can apply up to four base coats, depending on the customer's wishes, but the fourth application would involve a special process. A top coat is then usually applied to obtain particular friction characteristics. The coefficient of friction can be set at values between 0.06 and 0.18μ (ISO 16047)", explains the Head of Production.
The new production machines enable Thielco to provide a complete Geomet® 321 and Geomet® 500 package with different top coats for parts in all steel qualities and diameters ranging from M5 to M42, both with and without a thread, and up to a maximum length of 850 mm. Several 100 tonnes of screws and fasteners treated with Geomet® currently leave the production plant in Reuver every week – and the volume continues to rise.
Maximum customer satisfaction
Michèl Jacobi is a fan of AGTOS blast machines. "We're really satisfied with all the AGTOS blast machines. Along with supplying very high quality machines, the company also provides an extremely good service. Maintenance and care of the machines is also perfectly adapted to the needs of a company like Thielco. It's obvious that everything from A to Z has been really well thought out. I always say that you can see by looking at a machine, the level of quality that has gone into its manufacture", sums up Jacobi.