Posted on: June 12, 2018, | By Vivi, WayKen Project Manager
Not sure since when, the request of low volume manufacture is getting more and more. New technologies like 3D printing, robotics and automation all found their positions in prototyping and manufacturing. To take your design to prototype is one thing, getting into mass production is another thing. Low-volume manufacture is a gray area between rapid prototyping and mass production, which is mostly underestimated in manufacturing. The advantages of it include fast adaptation to the demand of the market, shortening time-to-market, minimizing the product inventory, and making production system flexible.
In another hand, the varieties and short lead time are also big challenges for a manufacturing enterprise. Almost all the standards and systems are designed for mass production, therefore, there is nothing that an enterprise could use for reference to low-volume production, instead, they have to make effectual practice through a multitude of trials. After years’ experience and investigation, WayKen has developed some efficient solutions for low volume manufacture service.
CNC machining is usually used for 1-10 off prototype, the advantages are very obvious: fast lead time, low cost, accurate, stable quality and so on. When it comes to low volume manufacture, CNC machining would be a good solution as well, especially for metal parts. So far as we know, die cast molding is usually the only way for mass production, when you only need dozens, hundreds or even thousands, investing a mold might not be that wise, regardless of the long lead time for a mold, the cost is not attractive either.
What brings down the cost, and what’s the difference of one off sample and low volume production by CNC?
When we talked about CNC manufacturing, many processes would be involved other than only milling, such as lathing and turning. When only one off sample is needed, it’s better to simplify the process, as each process would need a set up cost. The more processes needed, the more set up cost would be charged. The situation changes when the volume gets bigger. As well as the fixtures, sometimes the fixtures greatly improve the efficiency for bigger volume, you maybe get one part and dozens parts with the same schedule.
Benefits of CNC machining:
Wide selection of materials
Quick removal of large amounts of metal materials
Highly accurate and repeatable
Suitable for many different kinds of substrates
Scalable volumes from 1 to 100,000
Low investment in tooling and preparation costs
Urethane casting is also known as vacuum casting, with the master pattern created by CNC machining or 3D printing, a silicon mold could be made base on it, after that, the chosen PU casting material would be filled in the hardened silicon mold. By using this method, several polyurethane castings can be made from the initial prototype. Cast Urethane parts are also quick and inexpensive without investing any metal tooling when quantities are only dozens, and can be delivered within weeks in most instances.
If we use CNC prototyping for low volume plastic parts, the cost of dozens might be enough to build a tooling. The application of urethane casting is a fantastic complement of CNC machining, and also gives low volume manufacture more possibilities. It also allows us to make soft rubber parts, over molded parts, insert molded parts, as well as double injected parts.
Benefits of Urethane Casting:
Lead time for the molds is very short
Various polyurethane resins available for casting, as well as over-molding
Stable dimension and tolerance
Durable molds for 10-20 or more
Perfect for the pilot of complex parts
Plastic injection molding is a common method for producing large amounts plastic parts for consumer and engineering use. The process consists of injecting molten resin into the cavity of a metal die under very high pressure. This is then cooled down, which results in the creation of a hard shape. The process usually takes few seconds to minutes depending on the part structure and size.
Rapid tooling is a bridge tool between rapid prototyping and production tool. If the demand of the product is not huge, or you want to compress the new product introduction cycle, rapid tooling should be a perfect solution for you.
The initial investment in a metal tool is relatively higher, even for a rapid tooling. By using soft steel, the simplified tooling design will save you a lot of cost and time. Almost any thermoplastic can be used; therefore, there is no any surprise if you need mass production thereafter. A production tool takes at least 5-8 weeks to complete, but rapid tooling takes only in 15 days, and you can get thousands parts within a week.
Benefits of Rapid Tooling:
Free in choosing any plastics and resins for any application
Cost-effective for large volumes manufacturing
Mold frame sharing technology
Able to tool for millions of cycles
Stable and controllable in process
With more and more drastic competition in the market, consumers want their products with greater variety and customization. Low volume may lead the way in the future. It saves you a lot of cost, even the unit price seems relatively higher than mass production, but you don’t need to invest a great amount of money at the very beginning; it also saves a lot of resources, with the development of the technologies, you don’t have to put so much labor or machinery on it. Low volume manufacture gives you more design flexibility. It won’t greatly impart total order, even though you want to make some modification during production,
Hope this article gives you a guideline for your next low volume manufacture project. CNC machining, Urethane casting and Rapid tooling are supplement for each other. CNC machining might be the only solution for metal parts. If you only need dozens plastic parts and accept polyurethane as the compromised material, urethane casting is a very suitable method. If you are ready to go to the market, but not yet sure about the volume, rapid tooling might be a better option.