(English) Value of Design Thinking in Solving Problems through Metal Injection Molding
VALUE OF DESIGN THINKING IN SOLVING PROBLEMS THROUGH METAL INJECTION MOLDING
Design thinking is a non-linear, iterative process that majority of manufacturing and engineering teams use to explore and understand users, challenge assumptions, redefine problems and create innovative solutions to prototype and test their solutions. It necessarily involved five stages —Empathize, Define, Ideate, Prototype and Test—one of the most useful approaches to tackle problems that are ill-defined or unknown, and are a major bottleneck to accomplish a larger and holistic solution.
Amongst the diverse challenges faced by the manufacturing industry, a major one is sourcing the components and sub-assemblies through a right vendor/ process. More and more focus is towards making the supply chain leaner, thereby eliminating waste and also assuring of a lower number of variables. One of the simplest solutions that many designers have offered, is integrating of various discrete components.
MIM, or Metal Injection Molding, has been very successfully offering integration solutions that have enabled reduction in number of parts in a sub-assembly, although complexifying the design of the components. The technology has a unique feature to facilitate simplifying the complexity in a typical design in terms of the manufacturing of the part. MIM involves designing and manufacturing of a Mold to enable producing of large quantities of parts as per the design incorporated in the Mold. This could be in multi-cavity design thereby enhancing the productivity of the same. Complexity of the components can easily be incorporated into the Mold design by innovative and creative approach used by our Designers.
Excellent product designs often fail commercially due to high cost of production and inability to ramp up to large volumes quickly. MIM bridges this gap between designs to commercial success by its ability to make complex metal parts at economical cost and the fastest ramp up rate amongst metal manufacturing technologies. A 16-cavity MIM tool can ramp up production to a million parts per week in just few weeks from SOP (start of production). This makes it suitable for products in automotive, mobile phone parts & single use medical devices which need a steep rapid ramp up rate once the product is launched in the market to cater to the huge population that it addresses.
To cite an example, a variable nozzle turbocharger (TC) uses engines exhaust to feed air to the combustion chamber and increase efficiency. One of the most critical part in a TC is a tiny 4 grams part called Vane which has an aerofoil shape made of a high wear and heat resistant metal called HK30. In a single TC, 11 such parts are required which means that for 1 million engines, the total requirement is 11 million vanes. Engines with Euro 6 norms and above advocate a requirement of a TC, which makes the demand very large. MIM technology makes these Vanes at much lower cost than the conventional technologies and offers fastest ramp-up rate, compared to conventional processes such as CNC machining and/or casting.
Another example can be from a single use surgical device called laparoscopic titanium pins stapler. This device is used for stapling and dissection of internal organs. The metal Jaws which houses the Titanium pins and performs the stapling and dissection are extremely complex in geometry and made of very tough stainless steels such as SS17-4PH or SS 420. This being a single use device, the global demands are above a million per month. An investment in a single MIM tooling can make the part production commercially successful, as compared to conventional technologies.
Yet another interesting example is from mobile phone industry. Today, the largest selling mobile phone is having a sale of around 8 – 10 million per month. Challenge for meeting such numbers is once again complex geometry and high volume as well as the steepest ramp-up rate from prototypes to peak volume. The charger plug housing in this phone uses a MIM part with liquid silicon rubber over molding to make it IP68 level waterproof.
The conventional processes of metal manufacturing sometimes works against Design Thinking as designers have to be limited by DFM – Design for Manufacturability. MIM removes the traditional limits of DFM and gives designers the freedom to draw complex geometries which can be smaller, integrate the components thereby delivery superior product functionality.
MIM brings freedom also in terms of material and mechanical properties. In CNC process, a standard available raw material has to be chosen. Meanwhile, MIM allows the use of alloyed fine metal powders as the raw material and customised alloys can be created to suit a particular function. For example, golf wedges can be made to weigh heavier or lighter with the same size by varying the density of the material by changing the tungsten percentage in the raw material. Similarly, in automotive applications, certain properties like higher temperature resistance or increased elongation etc. can be achieved by varying the Ni & Mo percentages in the commonly used standard medium carbon steels.
In terms of prototype samples’ speed, MIM has various methods such as a soft tooling which can make 5000 samples for large scale test. Another faster way is called green machining, in which a standard moulded block is CNC milled to the part shape which is further sintered to get the MIM test samples. Various other complimenting technologies such as binder jetting 3-D printing are also an option to produce the prototypes faster. Today, there are innovations in MIM where a designer can see the actual prototype samples in less then a week after uploading the 3-D model.
Design Thinking paves the way for creating innovative products and the cycle can be complete only if these products can be made at the right time of demand without uneconomical stocking. A combination of automated 32 cavity molding tool and continuous sintering furnace can churn out finished parts in millions just in time. The amount of capital investment is also lower with MIM. As an example, a component which takes 15 minutes by 5-Axis CNC can be moulded in 15 seconds considering a 4 cavity tool. This not only lowers the cost, but also lowers the capital machinery investment. When complex metal parts can be made just in time, the overall savings leads to lower selling price and hence higher demand for the end product.
Lastly, designers have a critical role in considering the environmental impacts of their products and also of the processes used to create these products. MIM ranks highest in terms of lowest environmental impacts amongst metal manufacturing technologies. MIM can be envisaged as an additive manufacturing technology as it add material to form the part and there is no wastage of the raw material. CNC process, on the other hand, is considered as a subtracting technology generating tons of chips which again needs huge recycling cost and environmental impact.