Cleaning Automobile Parts: Raising Efficiency and Quality

February 15, 2011 11:42 am

Fulfilling ever stricter cleanliness requirements, and at the same time dealing with increasing cost pressure, is a challenge for the manufacturers of automobile parts. Requirements-oriented cleaning solutions are essential to this end, which result in improved component quality while reducing costs as well. Doris Schulz writes.
 
A great deal of cleaning effort is required in some cases in order to fulfil the requirements specified by the automotive industry for component cleanliness. Nevertheless, many companies don’t know what percentages of their manufacturing costs are generated by cleaning. The trend towards smaller and more economical engines is resulting in stricter requirements with regard to the precision of the relevant components, which in turn leads to more demanding requirements for parts cleaning. A requirements‑oriented, well matched cleaning concept often makes it possible to exploit optimisation potential throughout the entire production sequence, and to make production more efficient in general.
 
Reducing Costs with Flexible, Individual Parts Cleaning
Components which are produced in large lot sizes such as cylinder heads, crankcases and gearboxes are frequently cleaned in inflexible transfer systems which have been specially designed for a specific part. Thanks to modern, automated, inline cleaning solutions with robots, flexibility which is adequately flexible for production can be achieved within the cleaning step. Integrated into the wet zone, the robot comprises the handling and processing unit of the cleaning system, which precisely positions the workpieces at various treatment stations such as spray cleaning, injection flood washing, high pressure deburring and drying. Control is implemented by means of a standard CNC system, and simple programming is assured with an easy to use teach-in panel. Necessary adaptations to new or modified parts can be programmed quickly and easily by operating personnel.
 
The compact design of cleaning systems significantly reduces space requirements on the production floor as compared with transfer systems, and the mode of operation is usually more energy efficient as well.
 
More Efficiency for Batch Processes
Numerous components which are built into motor vehicles are cleaned in wet chemical processes with solvents, or with water-based cleaning agents in batch processes. The advantage is high throughput within relatively short periods of time, which means that a smaller percentage of overall costs are attributed to cleaning the workpiece. Cleaning often takes place in central systems. When parts with different shapes, cleaning requirements and/or types of contamination (for example cooling lubricants and polishing dust), or parts which are made of different materials are cleaned at the same time, there’s no guarantee that the required degree of cleanliness will be achieved for all of the workpieces. For best possible cleaning results, it’s advantageous to run the cleaning process in a decentralised fashion using different systems which are matched to the respective spectrum of parts, type and degree of contamination, and cleanliness requirements. This usually leads to reduced logistics and handling expenses.
 
A cleaning basket in which the parts can be well rinsed by the cleaning agent from all sides supports the process too. Good accessibility to the parts shortens the required cleaning and drying times, and reduces media carry-over as well. This results in shorter cycle times, increased throughput and a longer bath service life.
 
Exploiting Potential Savings from Alternative Cleaning Processes
Economic advantages can also be realised through the use of alternative processes such as CO2 and plasma cleaning. Amongst other applications, CO2 snow jet cleaning is used for plastic parts such as bumpers and mirror housings before painting or coating. This is a dry cleaning process based on environmentally neutral, liquid carbon dioxide, which is accelerated with compressed air and blasts the component to be cleaned. Difficult to access areas can be cleaned in a targeted manner in this way. Particulates and film-like contamination are gently removed by means of mechanical, thermal and chemical action. On the average, investment costs for cleaning systems of this type are as much as up to 50% less than for conventional, wet chemical processes. And operating costs are as much as up to 30% lower on the average, not least due to the fact that no energy intensive drying is required and cleaning can be integrated into the paint booth in a space saving fashion.
 
The same is true of plasma cleaning, which covers a broad range of applications thanks to the use of various reactive gases. This is also a dry process, and is used primarily where extremely low residual grease levels are required for downstream processes. Good preparation (e.g. activation) of surfaces for downstream processes is a further result of plasma cleaning, for example improved adhesion of glues and coatings.
 
Controlling and Documenting VDA Compliant Cleanliness
Procedures and services for controlling and documenting technical cleanliness in accordance with VDA 19 or ISO 16232, volumes 1 through 10, “Road vehicles – Cleanliness of components of fluid circuits”, represent a further exhibition topic for parts2clean. The same applies to systems for bath monitoring and media treatment, which also make an important contribution to reliable, economic cleaning in the automotive industry.