Sanjay Kumar - Additive Manufacturing Solutions

Additive manufacturing

Bed process

Bed system

Conventional manufacturing

Cold spray additive manufacturing

Direct digital manufacturing

Digital manufacturing

Digital micromirror device

Deposition process

Deposition system

Electron beam powder bed fusion

Investment casting

Injection molding

Laser powder bed fusion

Powder bed fusion

Powder bed system

Photopolymer bed process

Photopolymer bed system

Rapid manufacturing

Support structure

Wire arc additive manufacturing

AM is called solid freeform fabrication (SFF) because it can fabricate a solid object having form (shape) that is free from any limitation. Other manufacturing processes offer limited shapes, and are therefore not called solid freeform fabrication.

For example, in injection molding (IM) , the shape of the cavity of mold restricts the form of a solid object fabricated; the object therefore has no freedom to take any form other than that given by the mold.

Complexity in IM depends upon how complex a mold can be formed, how well the mold can be filled up during injection, and how well the mold allows the injected material to be ejected []. If there is incompetency at any stage of the process, it will affect the maximum complexity of the solid form that can be achieved.

Mold has disadvantages if a thin wall or a small pin needs to be made, a mold having thin cavity is required that is not be possible to be fabricated with ease. Similarly, if a narrow hole needs to be made, it may not be possible to make a mold having narrow protrusion for such requirement. Even in that type of molds, it is not possible to make objects easily. Even if it is possible to make objects from such molds, the molds will not last long to justify cost investment. Thus, if there is a design which consists of such features, IM is not a right choice to make such objects.

If the shape of an object in IM was not limited by the shape of the mold, it could have freedom to make any shape, but the freedom would not come free. The confining space of the mold has advantage that it does not let material go astray. In the absence of the confining space, right parameters need to be searched for the material to remain confined within a designated space. But due to the confining space offered by the mold, materials can be stacked rather fast. Otherwise, every bit of the material requires to be checked whether the material is at the right place before solidification or whether it is not shifted due to shrinkage after the solidification. When every bit of material takes attention, the process will not be as fast as in the presence of a confining space where such attention is not required. This is one of the reasons for the slowness of AM where every bit of material addition needs attention.

If there is something (e.g., mold) which gives a confining space, then after the fabrication of one object , another object can be fabricated and so onthis can go fast. This advantage is absent when there is no mold (or no confining space as an outcome). In AM, each object needs to be grown, even if the object to be fabricated is always of the same shapethere is no certainty that the two objects fabricated will have no difference due to the growth. Thus, a mold gives an advantage of repeatability. If the same object always needs to be fabricated, IM is a preferred choice []. This is the advantage gained with mold based process.

Thus, mold has given advantages . It has made IM faster than AM. It has given repeatability [], which has caused IM rather than AM as a suitable process for mass production.

But, if a customized product rather than mass production is priority, if fabrication of a product is more important than the speed of the fabrication, if an old product having guarantee in property due to the confining space is less preferred than an innovative product, AM is better than IM.

If a digital file needs to be changed frequently to make new products or to verify the design of a product, it can be expensive and time-consuming, if done through injection molding (IM). Since with each change in file, a new mold needs to be fabricated first for letting the fabrication of a new product to follow.

There is no requirement of a mold (an intermediate step) in AM. The lack of requirement allows AM to reach physical object stage from digital file stage without going through the intermediate step. Thus there is one step less in AM in comparison to IM, which is mold-based conventional manufacturing (CM) . The requirement of fewer steps makes AM a fast manufacturing process. That is why AM is called rapid manufacturing (RM) , but it does not imply that AM in general is always faster than CM . It only implies that AM is rapid manufacturing because the delay associated with the intermediate step does not exist in AM. Therefore, AM can be faster than those CM which get delayed on going through intermediate steps.