To get the best results from this process, product developers should be aware of the following limitations and potential disadvantages.

The form impacts the cost of this material it is bought in, as not all polypropylenes are molding-ready. It is thus necessary to buy the plastic resin in pellet form. You may notice that engineering-grade plastics are generally more expensive (as with POM and PC). Overall though, the more materials you buy, the better your cost-effectiveness will become, as producers and distributors often have high-volume discounts which translate into better prices for your project.

And overmolding adds cushioning and shock absorption to many common household items that might protect users from accidental injury.

Large, industrial plastic injection molding machines can cost over $200,000 and have additional costs that are related to skilled labor training, maintenance, monitoring, and even industry regulations. These types of machines are reserved for high-volume orders.

Insert molding involves placing a pre-manufactured component, such as a threaded fitting or an electrical contact, onto a mounting pin or other fixture in a plastic injection molding tool. During the molding cycle, thermoforming resin surrounds this insert and solidifies, thereby permanently sealing it into place.

Injection molding tooling for a mid-level order (around 1000-2000 small parts), can cost up to $10,000. For more complex geometries and large orders, the cost can go up to $100,000.

Some parts may not need secondary services, while others do. The cheapest parts fall out of the machine and into a box, but others will form attached to the gate. Those require post-process machining to remove the gate, but they are used because gating makes the overall process more efficient and less wasteful.

Overmolding also offers more opportunities to be creative by applying colorful designs to improve the appearance of the part as well as its performance.

If you want to impart special physical properties to the resin you're using, or simply defray the cost of using pure plastic resin, you can add additives. Commonly used materials like plasticizers and mineral fillers are among the cheapest that can be used, while products like lubricants and heat stabilizers can cost more than the polymer itself. There is a wide array of additives that impart a variety of properties, including glass fiber, ceramic fillers, pigments, UV stabilizers, plasticizers, and antioxidants. These materials can increase strength, impact resistance, durability, elasticity, and fatigue limit.

Mold setup costs include optimizing the process as well as physically setting up the materials and machinery to create your parts. These are part of the final price per part. The process will be optimized, and there may be some setup time that goes into preparations, which most companies will charge as its own flat fee. This may encompass processes like drying the resin, hanging the molds, arranging water lines, external troubles, and any type of sensors in the mold. It may also include any type of special cooling required or specific gating scheme that acts as a hot manifold system (which keeps runners hot enough to keep the plastic in them liquid).

This is just a partial overview of insert molding and overmolding. Are they the right solutions for you? Not sure how to apply them to your next project? Just contact our technical experts and we can offer helpful advice about how to get the best results from both processes.

Insert molding is used to put a rubber or plastic handle on a metal part, such as you might find on hand tools or kitchen knives. And insert molding is ideal for sealing wires and electrical connectors into permanent plastic housings that block out dust and moisture.

Saving money on injection molding can be helpful, but it’s important to be strategic around which areas you save money in. In order to maintain a cost-effective strategy for low cost injection molding, it is just as important to identify areas where trying to save money could cause bigger issues down the line as it is to find areas to lower the cost. The following tips will help you with both:

Remember that overmolding is rarely used to cover the entire base substrate. Instead, apply overmolding in sections. For each of these, keep in mind these useful design tips:

Injection molding cycle time takes up about 60% of final part cost. The part rate comes down partially to cycle time and partially to cavitation, which is covered in the next section. Generally, manufacturers will have set hourly rates they charge for their machines.

Overmolding starts with a base substrate, on top of which a relatively softer TPE or TPU material is bonded. The base can be metal or plastic, although, in this article, we will focus on plastic applications primarily.

Plastic resins, which can range between $.90-$2+ per pound, are the primary material used in plastic injection molding, while additives can range from more expensive additives like heat stabilizers to cheaper plasticizers. When choosing a resin, take into account the following considerations:

Besides physical properties, the color of the part can also be influenced, which is one of the most popular uses for additives. These providers will also sometimes establish partnerships with the thermoplastic producers to offer customers cheaper deals.

You should consider using insert molding for a few main reasons. The first is that your product application needs strong mechanical fittings to hold two or more parts together, typically for an enclosure or housing. Threaded nutserts are great for this but there are many types of snap connectors as well.

Injection molding costs from $10,000 or less to $100,000, depending on order size, part complexity, and other factors. Injection molding can be expensive to set up, but is cheaper over the long run, so it works best for large production volumes. There is a range of factors affecting the final price you would pay for injection molded parts, including the cost of the resin itself, tooling, cycle time, mold cavitation, and other details.

Set scrap rates will also go into the final cost of injection molding. These are for purging the plastic injection molding machines of previous plastics from the barrel and screws as well as reloading them with your plastic.

Plastic weight cost includes both the plastic formed into parts and the hardened plastic left over in the mold. You'll also have to cover the cost of the plastic weight, not only in the parts but in the runner, sprue, and gate as well (the runner and sprue are channels molten plastic flows through to get into the mold, while the gate prevents plastic from flowing out once it's inside). For example, if you end up with 4lbs of parts, and 1lb of leftover plastic that hardens in the sprue and runner, you'll pay for 5 lbs.

Another aspect to keep in mind is that for custom injection molds, the geometry has to be compatible with the machine used by the manufacturer. This constraint may affect your project (and possibly design), so it is best to make sure the company you are interested in can fulfill the order.

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Product developers should consider overmolding in order to improve the grip and texture on parts that need to be held in the hand or to protect the end user against vibration, heat, or electricity. Overmolding is also a great way to permanently bond rubber to metal, as is found on wheels and casters.

Extra steps such as finishing or post-processing services, inspection, and packaging represent an additional cost to the price per part and setup fees.

In this equation α is the thermal diffusivity coefficient and h max is the maximum wall thickness in millimeters. While the first is a material-specific constant, the latter is a design choice or requirement. As such, depending on the part's complexity, the cycle time can take up to two minutes.

If your provider is expected to deliver a ready or almost ready-to-use product, the packaging used may be the one your customers get to see directly. Some providers also offer personalized packaging services for this purpose.

Mold cavitation cost, another factor in price per part rate, increases with the number of cavities. Cavitation is the amount of identical cavities that produce parts per mold. The injection mold itself can cost thousands of dollars.

In this video, Gordon Styles, the founder and President of Star Rapid, goes into greater detail explaining how these processes work, and he gives examples of each. Be sure to check it out for more useful information.

You can either buy a ready-made injection mold or have one made for you. Ready-made mold use is a common practice and the less expensive option, especially in the electronics industry since standardization is quite prevalent. You can also have one produced for you, which is better for unique designs.

Injection molded parts cost varies based on mold upkeep, the time to form a part, and factors around the plastic. These include the part rate, the estimated amount of scrap (usually 3-5%), the plastic weight, and sometimes a mold maintenance fee, which covers the cost of injection mold warranties. The quoted price should also include any setup costs for the molds.

Once the base cools and is semi-hardened, the mold is then rotated to a new position and connected to a separate nozzle, gate, and runner system. The remaining void of the mold tool cavity is filled with TPE or TPU elastomer, creating the overmold that bonds to the substrate.

The first conventional injection cycle forms the substrate, using a standard thermoforming resin. This resin fills the gate, runner, and cavity system of only one part of the mold, while the section representing the overmold is blocked.

Injection molding tooling cost increases exponentially if we are talking about a large custom-designed part. From the operator's perspective, it is preferable to use small (desktop) injection molding machines (and even 3D printers) in order to fulfill low-volume orders.

If the substrate is a plastic base, then it’s customary to mold it in the same production cycle. This is done because it’s more cost-effective to make the entire finished piece at one time, rather than paying to transport and store semi-finished goods. But the more important reason is that the elastomer will adhere much better to a still-warm, semi-cured, and “sticky” substrate.

Overmolding uses a special type of plastic injection molding tool, one that has a cavity for the substrate portion and another separate cavity representing the overmolded section.

Mold cavitation is related to part size and design. If your part is relatively simple, single cavity molds are usually more affordable. However, if the part's geometry allows it, it is preferable to go for multiple-cavity molds to speed up the production process (making production less expensive over time). Larger parts may, however, not allow for this.

As a manufacturer, it is preferable to maintain the cycle time to as low as a number as possible, since that translates into the production of more parts in a given time.

Inserts should be used whenever a plastic case needs to be occasionally opened for service and then locked tight again, such as when performing routine maintenance or changing batteries. They cost a little more but that cost is offset by making a much more durable end product.

While there are many advantages to insert molding, there are some potential drawbacks that designers should be aware of.

However, to be able to do this, you should understand what exactly these areas are and how vital they are for your project. At Xometry, we offer the Xometry Quoting Engine to quickly get started on quoting your next injection molding project. Insert your requirements and designs into the Xometry's Quote Engine to get started and our experts will be in touch with you to start working out the details!

Trained personnel are required to validate the quality of the parts included in your order. Generally, however, if the part does not meet requirements (or expectations), the quality verification team of your provider is tasked with identifying the area and possible cause of the issue. This is, however, an internal process that is taken into account when you first make your order (no additional costs should be applied in this scenario).

Part packaging costs range depending on whether you require consumer-facing or just shipping packaging. Larger manufacturers can also make use of automatic packaging, which reduces the risk of error and damage.

Now, if that design logic is applied to a fleet of aircraft or millions of automobiles on an assembly line, then the reduction in weight and cost becomes substantial.

Overmolding is a special form of plastic injection molding. Unlike conventional molding, where a finished product is made in one cycle, overmolding requires at least one additional injection cycle using a dissimilar material. This method is also known as 2K overmolding, two-shot molding, or even multiple material molding.

Neither overmolding nor insert molding is restricted in their use to any particular industry or product type. Because both methods are so useful and adaptable, new practical applications are being found all the time that take advantage of their benefits. Here are a few examples:

Injection molding costs can vary depending on materials, equipment, mold cavitation, packaging, necessary certifications, and additional services employed. While your project may have strict requirements for the functionality of the desired part, there are multiple ways one can cut costs without sacrificing quality.

Secondary services will range in cost, though often you can get a discount for ordering both injection molding and secondary services from the same provider (this also saves on shipping costs for another facility). These may come in the form of:

Tooling costs depend on how complex or large your parts will be. In other words, if your part is complex (for example, if it has intricate geometry or dense walls), the manufacturer may need to use a special (i.e. more expensive) machine to complete your order.

There are some unique engineering challenges that designers might face when using insert molding. The advantages of added strength and versatility must be weighed against the need for a more careful design for manufacturing review. Here are some useful guidelines to consider:

In this article, we discuss insert molding and overmolding, the advantages of each, and the applications they’re best suited for. We hope these manufacturing insights, along with useful design tips, will help you get great results on your next plastic injection molding project.

The table below can be used to approximate the cost of plastic injection molding related to the most commonly used materials. These prices can vary, depending on the supplies and volume order.

Part inspection requirements costs for quality can include standard inspection or specialized certification, though specialized certification will cost more. The injection molding process itself can introduce defects of various degrees to parts (from cosmetic to critical). Some of them may be acceptable, depending on industry standards.

Which process is right for you depends entirely on your application. Keep in mind that they aren’t mutually exclusive molding methods because they serve different purposes. In fact, it’s not uncommon to find both used on a single product. Think, for example, of a power tool that has overmolded grips on the handle, but that also uses nutserts to bolt the case together.

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The process is not limited to just two materials, and can theoretically be expanded to include an indefinite number of additional overmolds. However, in practice, more than two becomes increasingly complex and expensive.

Get 7-day standard lead times on simple parts between 0.5 in. x 0.5 in. and 4 in. x 3 in. Upload your part to see if it’s eligible.

Some companies offer the possibility of additional certification to your parts, at a cost. This implies the involvement of specialized engineers that are also licensed and are legally capable of offering these certifications.

Inserts can be either male or female. Female inserts are used to make circular fittings inside the surrounding plastic. When these types of inserts have internal threads, they’re called nutserts. There are many advantages to using both male and female inserts to enhance a product’s appearance and utility.