Die caster worldwide is always facing a constant challenge of producing good parts as per the print requirement. A product should meet the various requirement as per the international standards, the customer's own standards & often other application requirements set by the end users.
The product must be free from casting defects like porosity, short filling, cracks, cold shuts etc:, then it must also conform to dimensional accuracy both as cast condition ( standard generally followed is DIN 1688 ) & after final machining which is print requirements of individual part. Also in many cases the physical property is of extreme importance which calls for post casting treatments of parts to achieve the desired results by carrying out various heat treatments as per designated temper codes like T5, T6 etc:. And last but not the least the visual defects are also a major criteria one should look into to get a defect free part.
Therefore we see in entire value chain each manufacturing steps is critical & important to achieve the desired quality level of following,
I would like to share a recent case study where two parts are integrated into one compact casting & it is a real challenge to cast the new integrated part to required quality level. The integration has made the part geometry complex in terms of unbalanced geometry, non uniform part wall thickness & several variation to be generated from one single master casting. The below photographs will give some idea of how the final part becomes intricate after it is integrated into one. The application is for Dual action break valve for heavy commercial vehicles.
This is mounting plate .
This is upper body, which is connecting the breaking system in the vehicle
This is a part which is a combination of mounting plate & upper body. In addition to integration the further challenges is to produce around 14 different variants from one single master casting depending on various port size - both the tap size & port length. This is a stupendous challenge to die designer as well as the die caster for getting the raw part as per the print requirement.
Considering the above requirements the die caster must take an holistic & systematic approach to meet the challenges.
It is of no doubt that die casting is a complex process because of high temperature & high pressure that is involved as a basic requirement. Each and every controlling parameter is important & plays a crucial role for quality.
Having said that I believe & practise the principle of "Theory of three" in die casting. Now what is this "Theory of three"? We all agree that there are three main input for die casting. The first is the die, the second is the metal & third is the process. Therefore comprising of all three ingredients will lead to quality casting. The typical control of all three application in a critical way is "Theory of three".
Once the die designer is getting a task for development of a component, he should have a clear knowledge of end use and the kind of field condition that part is going to sustain. Secondly the requirement as stated in drawing & different standards that are applicable should be well known to the designer. The die designer must arrive at the optimum design for best casting quality, maximise die life, ease of die maintenance & usage of standard parts to the best of possibility. The engineering & production people must work in tandem with designer to ensure that die design is meeting all the requirements.
The metal comes the second most important part. This starts from the stage of receiving Raw material to your plant to final preparation & transfer. Quite often Raw material is not given the due importance & as a result quality is affected. It is important to establish a robust mechanism for Raw material testing & handling system in the plant. Qualifying the chemical composition test is not enough to ensure good raw materiel. Many other test like grain structure, sludge factor, impurity level etc: are equally important. For example if you have crack problem in casting the root cause may be inherent in your alloy quality rather than process & die design. Sometime the range of elements in the alloy can be lowered or to be kept in higher side to avoid defects in casting.
The last factor is the process which is a combination of the PDC machine & molten metal handling. The machine must be maintained in optimum operating condition as recommended by manufacturer all the time. The process parameter setting to be standardised & regular audit is of prime importance. One quick check point which in many shops are sometime missed of the PDC machine is the dry shot velocity. Similarly strain gauging of PDC machine to keep the platen alignment & load distribution is a must. In addition to that consistent setting & freezing of machine parameters to be followed. Besides the preparation of melt have to be standardised & followed with strict adherence. After receiving a good Raw material if the melting & holding process is poorly handled then one can land up to huge rejections.
To conclude the "Theory of three" it is evident that for quality casting the three factors namely Die, Metal & Process must be seamlessly integrated each time & every time. One can not ignore any one of this three most important ingredients which will produce quality casting.
The product must be free from casting defects like porosity, short filling, cracks, cold shuts etc:, then it must also conform to dimensional accuracy both as cast condition ( standard generally followed is DIN 1688 ) & after final machining which is print requirements of individual part. Also in many cases the physical property is of extreme importance which calls for post casting treatments of parts to achieve the desired results by carrying out various heat treatments as per designated temper codes like T5, T6 etc:. And last but not the least the visual defects are also a major criteria one should look into to get a defect free part.
Therefore we see in entire value chain each manufacturing steps is critical & important to achieve the desired quality level of following,
- Casting defects
- Dimensional defects
- Physical property
- Appearance or Visual defects
I would like to share a recent case study where two parts are integrated into one compact casting & it is a real challenge to cast the new integrated part to required quality level. The integration has made the part geometry complex in terms of unbalanced geometry, non uniform part wall thickness & several variation to be generated from one single master casting. The below photographs will give some idea of how the final part becomes intricate after it is integrated into one. The application is for Dual action break valve for heavy commercial vehicles.
Considering the above requirements the die caster must take an holistic & systematic approach to meet the challenges.
It is of no doubt that die casting is a complex process because of high temperature & high pressure that is involved as a basic requirement. Each and every controlling parameter is important & plays a crucial role for quality.
Having said that I believe & practise the principle of "Theory of three" in die casting. Now what is this "Theory of three"? We all agree that there are three main input for die casting. The first is the die, the second is the metal & third is the process. Therefore comprising of all three ingredients will lead to quality casting. The typical control of all three application in a critical way is "Theory of three".
Once the die designer is getting a task for development of a component, he should have a clear knowledge of end use and the kind of field condition that part is going to sustain. Secondly the requirement as stated in drawing & different standards that are applicable should be well known to the designer. The die designer must arrive at the optimum design for best casting quality, maximise die life, ease of die maintenance & usage of standard parts to the best of possibility. The engineering & production people must work in tandem with designer to ensure that die design is meeting all the requirements.
The metal comes the second most important part. This starts from the stage of receiving Raw material to your plant to final preparation & transfer. Quite often Raw material is not given the due importance & as a result quality is affected. It is important to establish a robust mechanism for Raw material testing & handling system in the plant. Qualifying the chemical composition test is not enough to ensure good raw materiel. Many other test like grain structure, sludge factor, impurity level etc: are equally important. For example if you have crack problem in casting the root cause may be inherent in your alloy quality rather than process & die design. Sometime the range of elements in the alloy can be lowered or to be kept in higher side to avoid defects in casting.
The last factor is the process which is a combination of the PDC machine & molten metal handling. The machine must be maintained in optimum operating condition as recommended by manufacturer all the time. The process parameter setting to be standardised & regular audit is of prime importance. One quick check point which in many shops are sometime missed of the PDC machine is the dry shot velocity. Similarly strain gauging of PDC machine to keep the platen alignment & load distribution is a must. In addition to that consistent setting & freezing of machine parameters to be followed. Besides the preparation of melt have to be standardised & followed with strict adherence. After receiving a good Raw material if the melting & holding process is poorly handled then one can land up to huge rejections.
To conclude the "Theory of three" it is evident that for quality casting the three factors namely Die, Metal & Process must be seamlessly integrated each time & every time. One can not ignore any one of this three most important ingredients which will produce quality casting.
