There are very similar between plastic overmolding and 2k injection molding, simply explain there is two point difference.
1, Plastic overmolding is using normal single nozzle injection molding machine to produce the two different type of plastic parts in one ( or two different color of plastic parts in one solid part), overmolded process means move the first part (substrate part) or melt inserts (insert molding) to the subsequent mold (over mold) and molding to get the final part. 2K injection molding is using the 2K injection molding machine to produce two or three materials (colors) in one solid part, molding process is complex but fast, efficient, and high quality, 2k molding unit cost is less than plastic overmolding cost.
2, Compare to plastic overmolding and 2k injection molding, 2k injection molding has high quality and high production efficiency, but since the 2k injection molding machine is too expensive, so sometimes use over-molding to replace it, on the other hand, overmolding cost is high than 2K injection molding cost, but plastic overmolding can use any normal injection molding machine to produce the overmolded parts, so for low volume of 2 color molding, plastic overmolding has more advantages, and some of parts can only be done by plastic overmolding process.
2K plastic molding
Two color molding
Blow is the relation to plastic overmolding and 2k injection molding.
Plastic Overmolding is an operation in which two or more mediums (substances) are merged to form an ending molded product, plastic over-molding needs to make two separate molds, one is substrate (first mold), the second mold is called over mold (usually a TPE material for the second mold), but if the substrate is metal parts or brass parts, this type of over molding we normally call insert molding, and insert molding only need one mold to finish the process. The plastic over molding materials majorly used are thermoplastics (TPE) and rubber, or the same material but different colors. During over molding, the activity that happens is either mechanical or chemical which leaves the two substances bonded.
Plastic Overmolding process is producing the molded part (substrate) from the first mold and move it to another related over mold, the substance can be used to combine the surface molded with the molding substrate. The molded material can otherwise be put back to the surface it was extracted from and the overmolding substance added. Types of overmolding include two shot sequential overmolding, insert overmolding or multi-shot injection molding.
Two shot sequential plastic overmolding is where the molding machine injects the first plastic resin into a first mold cavity (both molds in one molding machine), once formed then move the molded part to the second over mold immediately and close the mold and injecting second material, using the first component as an insert for the second shot using a different material or color, requires special injection machine which has the two injection units.
Insert over-molding uses a pre-molded insert placed into the mold before injecting the second material, if it the inserts are metal or brass, then we call metal insert molding, this overmolding process which we used a lot, Multi-shot injection molding injects multiple plastic resin into the mold cavity during the same injection molding cycle.
Advantages of plastic over molding
Compare to 2k injection molding, plastic over molding is more easy to make, you can use a normal injection molding machine to make 2 or 3 different colors in one molded part, or make two or three different materials in one ending part.
For some small quantity of two-color molding parts projects, you do you not need to invert or hire 2k injection molding machine, use over molding process is the best and low cost to meet customers requirement.
It increases the design diversity and also exalts the end product towards many materials composition.
There are less secondary activities or processes carried out on the end products. This reduces any cost of labour. Also, after manufacture, no more costs are incurred.
The parts have a high level of stability and constitution since after being left to mechanically inter-lock they become one.
Product over molded using plastics have high resistance to vibrations and shock due to the plastic resins having been structured perfectly.
The end products are of desired quality such as firm components and eye-catching designs.
Metal insert overmolding
Disadvantage of over molding
Since over molding process is moving the first molded substrate part to another over mold, so the tolerance is not as good as the 2k injection molding process.
the production capacity is not as efficient as 2k injection molding, because working on the over molding you need use robot or manual jobs to put the substrate into the over-mold, this will take time and the molding parameter sometimes is not stable, especially two or more substrates in one over mold, this cold caused more issue and increased the waste rate, and this waste is double (substrate and over mold).
With over molding, there are less available choices in terms of plastic compatibility.
There are no secondary practices carried out on the end products of over molding. Activities and adjustments come to a full stop when the molding material becomes cold.
In cases where products are scarce, it is expensive to run such an operation. Sincere you need use person to put the substrate into over mold, so the cycle time is increased and the production cost is increased accordingly.
2k injection molding is a manufacturing process used when referring to molding two materials/colors into one plastic part. This plastic molding technology blends two materials or two different colours materials into one ending plastic part by using 2k injection molding machine.
2K injection molding
The chemical bonding process involved in this process takes place because they are able to merge two or more material into one part. When using 2k injection molding technology process, the material selection will be the key point factor to the success of the project or not.
This is an industrial activity that entails directing two totally opposite polymers into a ready product.
Over molding is for some small scale production volume compared to the 2k injection which is majorly large production scale.
With the over molding process, for another process to happen, the material used to mold must get cold to be removed whereas.
With 2K injection molding it is different. The polymer is usually still hot and flexible; hence more operations can still be carried out.
Once an object is made using over-molding it is locked mechanically with the other substances whereas it forms a chemical bond that entails its molecules bonding in 2k injection molding.
The 2K injection molding procedure can house diverse ideas such as the use of many different materials thus high-quality end product, opposed to the 2K injection molding procedure, the over molding activity can have some compatibility issues more so plastics.
When over molding, you are restricted to over-molding a metal with a plastic a few cases of a plastic and a plastic.
While in 2K injection molding there is a wide range of materials that can act as the molding substance or be molded on.
multiple shot injection molding
double injection molding
two-shot injection molding
Advantages of 2K injection molding
The parts are strongly fitted and molded thus components or rather end products become more durable.
The appearance in terms of aesthetic value or beauty is high since many colours can be blended in the molding stages.
There are reduced costs since all manufacturing procedures are completed in the injection stage.
Finally, custom made products can be made to suit the user’s preferences
Disadvantages of 2K injection molding
When such a process is introduced at once, the mold cost is expensive, and you must run this mold in the 2K injection molding machine, this machine is expensive than the single color injection molding machine, it becomes expensive compared to introduction through bits and bits. Ultimately, this idea is outweighed by the fact that the expenses will be recovered due to the lack of labor cost and assembly costs.
You may have question when do you need to use over molding and when should you use 2k injection molding process, there is some simple suggestion,
If the quantity is not so high, maybe only a few thousand or ten thousand, then use over molding process, this will save some mold cost for you.
If you need over a half million of parts, then 2K injection molding is the best process to save cost for you.
some of the parts only can use over molding and some of parts can be done by double injection molding process only, this is depending on the part structure, if you can not sure about this, you are welcome to send your data to [email protected], we can check this for you and offer you a price for your reference.
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