Posted on: May 4, 2018, | By Candy, WayKen Marketing Manager
1. Definition of low volume production
As we know, it(low volume production) refers to orders with a relatively small number of production units, ranging from tens to hundreds. Of course, depending on different product conditions, there is no strict number limitations to distinguish mass production and low volume production. Mass production is characterized by stable product structure, high degree of automation, long line of production and product standardization. Compared with mass production, however, low volume production has a much shorter production time and products are not necessarily standardized.
2. Application and manufacturing process for low volume production
Low volume production is generally applicable to small batch trial production verification in the research and development stage, or for some partly customized products in low volume. There are several kinds of technology for low volume production. Currently, vacuum casting and reaction injection molding (RIM) are most widely used. These technologies are characterized by high efficiency, fast speed and low cost, which can effectively solve the cycle and cost of new product development for company.
2.1 Vacuum casting
Vacuum Casting refers to preheat, defoam, stir and cast castable materials by the original models under vacuum condition. Besides, processed by making secondary curing molding in a thermotank with temperature from 60 °C to 80 °C for several hours, to create a silicone mold. After that putting materials such as PU, similar POM, or ABS to casting under vacuum in the mold to clone the same copy as the original master. Silicone mold is popular with rapid molding process. With good toughness, vacuum casting can produce plastic parts with complex shape structure, fine surface features, dimensional stability, and material properties. It is suitable for low volume production that meets certain functional requirements during product development.
The Advantages of Vacuum casting in low volume production as follows:
-Shorter production time from processing prototypes, turning silicone mold to casting products. Entire cycle only takes a few days.
-The diversity of material choices. The two-component polyurethane PU is used as vacuum casting material, including physical properties similar to commonly used engineering plastics such as ABS, PP, PA, PC, PMMA, rubber, high temperature resistance, and fire protection.
- Stable dimensional accuracy. Room temperature vulcanized silicone rubber has excellent simulation, chemical stability and extremely low shrinkage, which can reproduce the fine features of the master parts and ensure the dimensional accuracy. Standard copying accuracy can be controlled within ±0.15mm/100mm, with the highest precision reaching ±0.05mm.
- Trial production of complex process structures parts. The silicone mold of vacuum casting can be easily demolded without the need to design draft angle, complex structure can be directly out of the mold, and easy for secondary casting, metal insert, investment casting, castable coloring etc..
Reaction Injection Molding (RIM), also known as low pressure or high pressure perfusion. It is a new technology applicable to the production of rapid molded products. It mixes two-component polyurethane materials, and then injects them into a RTV mold under normal temperature and low pressure environment, forms products through chemical and physical processes such as polymerization, cross-linking and curing of materials. It has advantages of high efficiency, short production time, simple process and low cost. It is suitable for low volume production in the product development phase, as well as production of low volume, simpler structure covers and large-scale thick-walled and uneven-walled products.
The advantages of RIM are as follows:
- The aluminum alloy mold or the ABS mold can be directly processed by CNC. The low-cost mold material can be selected. Mold lifespan can reach hundreds of times and thousands of times, and the mold can be secondarily repaired.
-The product molding time is short, generally 20-90 minutes. Large-size workpieces are more stable and can control the accuracy of ±0.20mm/100mm.
- High strength, high elongation material characteristics, and strong weather resistance, can increase the mechanical properties and impact resistance by adding fillers and glass fiber composite materials. Applicable to high-performance components such as automotive exterior enclosures, construction machinery, etc. that meet harsh operating conditions.
- It can produce hard, semi-rigid and soft self-skinning foams, providing ultra light weight, safety, comfort, energy saving and environmental protection materials for humanized products such as medical devices and automotive interior parts.
- Applicable to large-scale covers with simple structure. The product does not require uniform material thickness. It can satisfy free design and curved surface shape with different wall thickness from 3 to 20 mm.
3. Advantages of low volume production
When it comes to the advantages of low-volume production, reducing cost is the most obvious. It is well known that mass-produced products are generally manufacturing molds before production, and the molds cost are usually very expensive.
The second advantage of low volume production is shortening production time. For mass production, the production time of molds generally takes at least one month, then comes to mass production it takes more time.
While by using above-mentioned several technologies for low volume production can greatly shorten the production time to make a fast delivery. The third advantage is reducing risks.
Especially for some customized products developed by many companies, the prospects for trial production is not clear before products come into the market. After the prototypes are completed, the products will be launched to various sale channels and markets for testing. After geting feedback from the real market , order quantities will also be evaluated. Then manufacturers decide to wether factories make mold and start mass production or not. This method could avoid loss from opening mold directly without any market feedback. Moreover, it can help improve the design in some ways.
4. WayKen's low volume production case analysises
As experienced manufacturer in this industry, Wayken has provided low volume production service for worldwide customers from different industries like automotive, aerospace, FMCG and Defence etc..
Here is a low volume production case we produced for a customer in the automotive industry. We received a customer's request to make 6 sets of two auto parts. After in-depth communication and confirm product details and requirements, we started to carry out production of the project:
Step 1: Our engineers conducted 3D data analysis, patched entities, identified the best disassembly solutions for prototyping.
Step 2: Programming, the programmer performs the process path parameter design, physical cutting simulation verification.
Step 3: Material Selection, we choose the most economical ABS for prototype production.
Step 4: Prototype CNC Machining. We started processing from the B-side of the workpiece, taking a total of 8.5 hours from the milling plane to the finishing machine, and then filling the gypsum turning face-up to start the processing of the A-plane. Processing the A-plane takes a total of 6 hours. After the processing of A-side and B-side was completed, our manual masters began to go to the frame and plaster to disassemble the pieces. The prototype began to appear. We polished the ash, and the prototype was completed.
Step 5: Prepare to make a silicone mold. Paste-type adhesive tape - Dividing line - Support - Fixed vent - Molded frame - Fixed prototype
Step 6: Silicone Molding, Silicone Metering - Stirring - Injection Molding - Vacuuming - Baking – Curing
Step 7: Open the mold, remove the prototype and cut the block
Step 8: Wrapping paper and closing the mold - setting the pouring port - pouring material ratio
Step 9: Vacuum Casting - Oven Curing - Mold Opening - Workpiece Take - Secondary Curing if Necessary
Step 10: Post-processing, manual repair - Bottom ash - Grinding - Spray primer - Spray paint - Baking - Finished products
Nowadays, as market demand changes rapidly and encounters with fierce competition, there will be more and more customized products in low volumes. Compared to the stability and unity of mass production, low volume production can meet the diversity needs. What’s more, it will be more and more popular in the future. After all, different things can always get higher value. If you have similar products that need to be produced in low volumes, welcome inquiry us Wayken. For more information, please visit our website www.waykenrm.com.