Injection molding is a manufacturing process of injecting molten plastic materials into a mold and then cooling and solidifying them to create molded products. It is ideal for mass production of products with complex shapes and a huge part in the area of plastic processing. Molten plastic is injected into a mold, which is a hollow metal block to form certain fixed shapes.
The injection molding process involves six major steps, including clamping, injection, dwelling, mold opening, and removal of products.
The Advantages of Injection Molding
Injection molding is suitable for very intricate parts, and it allows you to include more features at very small tolerances.
Wide Range of Materials
There is a wide variety of materials available for injection molding. Materials like thermoplastic rubber, antistatic plastic, chemical-resistant plastics, infrared biocompatible, and a range of standard materials. There is also an endless choice of colors with color compounding or masterbatch coloring.
Low Cost Per Part
The injection molding tool requires a high initial investment. However, the cost per part is very low. Injection molding can perform the entire process at once, unlike other techniques that require multiple operations.
Injection molding tools have a cycle time of as low as ten seconds. This means that you can get many products quickly. Parts that use specialist materials and have a lot of features may take longer but still have high mold cavities per hour.
The injection molding process produces less waste with its high part repeatability. Most of the parts like the runners and sprues can be reground and the material reused.
The task of obtaining quotes from injecting molders for projects requires procurement and purchasing managers. The cost varies greatly depending on the input, including prototypes, drawings, and sample parts. Designers check the inputs to establish the best molding solution and redesign the part to maximize manufacturing efficiency to increase the components produced with each cycle.
Typically, mold made with more cavities, tighter tolerances, and a longer production life take longer to construct and cost higher upfront. These high-quality molds yield long-term savings, require less maintenance, and last longer.
The Cost of Injection Molding
The true cost of injection molding may seem slightly higher than other processes like CNC machining or rapid prototyping. Still, the ability to scale and manufacture numerous parts makes it cost-effective for large-scale production. The cost of injection molding is determined by various factors with one of the main factors being the time it takes to produce tooling.
The complexity of the parts will increase the manufacturing costs, while simple parts without undercuts or surface finishes are cheaper to produce. The plastic material used also impacts cost.
Factors That Determine the Cost of Injection Molding
The Core Metal
Molds made from aluminum are ideal for shorter production runs. This will also help if the mold will not be used long-term. However, aluminum mold may cost more in the long-run if the project requires the mold to last for many years.
The Number of Cavities
A mold with fewer cavities will require less tooling work and time, as well as a lower cost. To maintain the highest level of productivity, it is best to maximize the cavitation in the mold. Experienced mold makers recommend creating one mold per part as opposed to creating a family mold. Family molds tend to produce low-quality products and have more downtime due to maintenance issues. This is because they are created with various assorted parts.
Bridge tooling can be used between the product end development and the beginning of production. It is a fast method that is cost-effective and achieves high-quality low to moderate volume parts. It is ideal for a rapid project that does not require high volume production.
The mold base contains all the mold inserts, components, and cavities. The base cost is determined by the type of steel used, mold size, and the customization required. Mold bases usually come in standard sizes and are customized further to meet the specific project’s requirements.
The complexity of part plays a major role in determining the cost of the mold. This includes the surface finish of the final part and the number of undercut features required. Parts with tight tolerance also contribute to the complexity of the mold.
Cores require customization, which includes placement of cores, ejectors, cavities and cooling lines. The cost is also impacted by the steel used in the tool. Hardened steel has a long production life, lasts the longest and is more expensive to the machine.
Machine Time Required
From the manufacturer’s viewpoint, time equals money, and longer cycle times
mean more energy and maintenance costs. The setup time and type of mold
influence the amount of time a machine needs to complete an order.
The plastic material required also impacts the cost. There are various types of plastic material, including conductive, UV resistant, and fire retardant. Other features include specific colors or transparency, functional at high or low temperatures.
Some special properties increase the price of the material and affect the price of the mold tool. This is because these materials can only be used with a steel mold tool. Some of the materials selected may be unnecessary and increase the cost of molding exponentially.
Injection molding has self-regulated and automation in the process, which lowers the labor cost. However, other key elements affect labor costs. Offshore tooling offers low labor costs though the rate can increase due to higher shipping costs and economic growth.
There are types of equipment, and each requires a different level of maintenance. For example, electric hybrids typically require less maintenance than hydraulic machines. Additional services like the development of a prototype for your part or a tool relocation can increase the initial costs of labor.
Rapid Axis offers extensive capabilities in injection molding and vacuum forming. We offer high-quality, efficient, and affordable services to meet all your needs. From small medical device prototypes to large enclosure production runs, we meet all your expectations with quality presses and quality staff, we deliver your tool in time. Our lead times can be as short as two weeks to the first article for some projects. All commercially available materials are supported and any post-process finishing. Get in touch with us about your project today and we’ll have a free quote ready for you in as little as one business day!