Effective paint preparation for truck trailer chassis and frames

Fully automatic continuous hanger shot blast machine - custom engineered for a wide work piece range and space constraints at the customer location

The protective paint on truck trailers used in construction, demolition and waste disposal, generally must be able to withstand heavy loads.  Essential for achieving excellent functional and cosmetic paint properties is the optimum pre-paint surface preparation. In order to improve the quality of its shot blast process and to reduce production times and costs, the Hüffermann Transportsysteme GmbH purchased a fully automatic continuous hanger shot blast machine RHBD 34/20-K from Rösler. Due to the tight space constraints at the customer location this machine had to be custom engineered in its entirety.

The Hüffermann Transportsysteme GmbH founded in 2013 has been a true pioneer in the field of truck trailer manufacturing. With around 150 employees the company, located in Neustadt/Dosse in the state of Brandenburg, manufactures heavy duty truck trailers, semi trailers, frames for dump trucks, container trucks and cranes as well as quick change systems for waste disposal & winter service and load securing systems. Through constant technical improvements this company has become the undisputed international market leader with regard to quality, expected service life and resale value of truck trailers. Hüffermann has earned this leadership role by continuous professional training of its employees and investment in state-of-the-art manufacturing systems for steel fabrication, painting and final assembly.

Improved quality at lower costs through automatic shot blasting

An example of this forward looking company philosophy is the new, recently installed, continuous Rösler shot blast machine RHBD 34/20-K for the surface preparation of various trailer chassis prior to hot dip galvanizing and painting. This machine replaced a costly and time consuming manual shot blast process that took two employees between three and five hours to prepare one chassis. Stephan von Schwander, general manager at Hüffermann explains the key requirement: „Depending on the chassis type, with the automatic shot blast process we can reach between 90 and 95 percent of the surface areas. The remaining five to ten percent we blast manually. For this reason, the new automatic shot blast system had to be placed directly adjacent to our existing blast room. Other requirements were relatively long maintenance intervals, high uptimes and easy exchangeability of the blast turbines and simple, intuitive operation of the new shot system. Based on this requirement list the general manager requested quotes from five equipment manufacturers, from whom two were pre-qualified. Stephan von Schwander continues: "Key factors in our decision for Rösler were the excellent after sales service, the fact that Rösler manufactures all its equipment in Germany, the excellent value we received for our money and the flexibility of the Rösler engineering team."

Automatic shot blasting of around 20 different steel fabrications

The RHBD 34/20-K allows the continuous blast cleaning of trailer chassis and frames with dimensions of up to 3.2 (W) x 13.0 (L) x 2.0 (H) meters. The hanger transport system has been designed for a payload of maximum 10 metric tons. The trailer components are initially transferred into an inlet chamber. Once the chamber has been closed by a space saving sliding door, the shot blast process starts. Stephan von Schwander describes the process as follows: "Every one of the individual steel fabrications is different. This normally requires specific blast parameters reflecting the size and design of the about 20 different component types. By the unique location and angle of the turbines on the blast chamber we can blast clean all our fabrications with one program. The only variable is the transport speed. This fact makes the operation of the Rösler shot blast system very simple and easy".

The RHBD is equipped with twelve easy to maintain H 42 turbines allowing an optimum media acceleration and cost effective shot blast process. Each of the twelve turbines has an installed power of 11 kW. The turbines are placed in a ring around the blast chamber and are mounted at an angle that allows the ideal blast coverage of the work pieces including the frontal and rear surface areas.
Like all Rösler shot blast machines the blast chamber of the RHBD at Hüffermann consists of 8 mm thick manganese steel. In addition, the walls exposed to the blast stream are further protected against wear by 25 mm thick overlapping and easily replaceable cast steel liners.
After completion of the blast cleaning process the various steel fabrications are passing through an outlet chamber before automatically being transferred to the manual blast room. Because of the excellent cleaning results achieved by RHBD system, only a few surface areas like certain corners not reached by the automatic blast process must be touched up manually. Depending on the chassis type this takes between 10 to 20 minutes. Mr. von Schwander is understandably pleased: "With the Rösler shot blast system we achieve a significantly higher throughput with a consistently excellent quality; and all this at considerably lower costs."

Tailor-made equipment design

The space constraints at the equipment location at the customer premises posed quite a challenge for engineering and installation. For example, the available space between the building columns was only 5.6 meters, leaving very little room for placement of the turbines, considering that the steel fabrications to be blasted are 3.2 meters wide. Because of these space constraints the blast media cleaning and dosing had to be placed above the hanger transport system. Towards this goal the height of the building roof had to be partially increased. A small building addition was necessary to accommodate the dust collector and the elevator. The media return of the existing manual blast room was integrated into the media return system of the RHBD. Stephan von Schwander remembers: "The Rösler service engineers were excellent meeting all the challenges coming up during the installation phase."