Month: May 2017

How to Avoid Common Injection Molding Defects

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When working with any assembling procedure, various deformities unique to that procedure ordinarily happen. This is true across many processes and industries, including plastic injection molding and high volume injection molding.

There are a few normal infusing forming abandons; be that as it may, an injection molder who is cautious about quality, similar to our group at Quality Mold Shop, will have the capacity to deal with these injection molding deformities, limiting or dispensing with them all together.

These six most common plastic part defects can all be traced to one of three sources: the resin or additives used, the injection molding process, or the mold itself.

Resin and Additive-Caused Defects

Two common defects caused by issues with the resin or resin additives used during injection molding are delamination and discoloration.

Delamination

Delamination, when a completed part has a layer of flaky material at the surface, hurts both aesthetic of your part and its strength. Created by humidity contamination of the resin pellets or by other defilement of the dissolved resin with a different resin, or by discharge specialists in the mold, delamination is the aftereffect of the resin being kept from bonding.

Various strategies, both basic and more mind boggling, can be utilized to counteract delamination. On the off chance that dampness is the issue, pre-drying the resin pellets or expanding mold temperature will offer assistance. In the event that form discharge specialists are the cause, a mold redesign that places more focus on the ejection mechanism will help to eliminate mold release. If it is caused by cross-contaminated resins, that will need to be replaced with virgin material.

Staining

Staining is basically when a completed part is not the same as proposed color. Brought on most usually by extra pellets in the container, excessively hot barrel temperature or remaining resin in the feed zone, the issue can be tended to by altogether flushing the container and bolster zone of a machine in the middle of procedures, subsequently avoiding staining as is normally done. Purging compound can likewise be successful to expel undesirable shading or resin.

Process-Caused Defects

In spite of constant advances in injection molding innovation, process-derived injection molding defects still occur. Two of the most common are burn marks and flow marks.

Burn Marks

Burn imprints are surface imprints, in some cases progressing to debased plastic, that are brought about by either caught air which ends up overheated or genuine resin that overheats. There are three approaches to keep away from burn marks: diminish resin injection speeds, which will bring down the likelihood of air getting caught; include or optimize venting and degassing systems; or reduce the mold and/or melt temperature.

Flow Marks

Flow marks are lined patterns, regularly wavy, or discoloration on a part surface. They are most generally created by resin cooling too rapidly or incorrect gate location. In the most ideal situation, flow marks can be wiped out by expanding injection speed and weight, which will guarantee uniform filling and cooling. In the direst outcome imaginable, a mold upgrade with an accentuation on maintaining a strategic distance from sudden stream heading changes and entryway area might be vital.

Mold-Caused Defects

Flash and short shots are two of the more typical injection molding imperfections brought on by mold outline or upkeep issues.

Flash

Sometimes known as burrs, flash is the occurrence of thin, wafer-like protrusions on a finished part caused when melted resin escapes the mold cavity. Most common along the parting line or up an ejector pin, flash can be caused by excessive injection speed or pressure, in which case the fix is a simple reduction. More often flash is due to poorly designed or severely degraded molds, in which case a redesign or retooling is required. Flash can also be caused by too high of a mold temperature and excessive barrel heat.

Short Shot

A short shot is when a dose of resin misses the mark regarding filling the shape. It can be brought about by endeavoring to utilize the wrong resin type or by poor process settings, yet is most normally created by door blockages or too little of an entryway distance across, a typical issue because of too low weight or insufficient warmth. On the off chance that a higher soften file resin or expanded dissolve temperature doesn’t take care of a short shot issue, you may need to upgrade the runner framework to advance stream.

Plastic Injection Molding vs. 3D Printing

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3D printing is a relatively new technology, and with its rise, manufacturers of plastic goods are excited to explore the possibilities of manufacturing using the 3D printing process. But what are the capabilities of 3D printing? Can 3D printing replace injection molding entirely as a way of producing plastic parts?

This is where you have to be careful. While 3D printing is a brilliant and promising technology that has very useful applications in the manufacturing process, it’s not quite able to replace the standard injection molding process just yet. Learning about the differences between plastic injections molding and 3D printing can help you to get the most out of each process.

What Is 3D printing?

3D printing is basically what it sounds like. During the manufacturing process, a special 3D printing machine is used to manufacture a plastic part through printing layers of the material onto the part until it’s complete. As with regular printing you’d do at home, the 3D printer is linked to a computer with a finished plan of what the part should look like once it’s done.

The benefit 3D printing has over injection molding – and the reason why many manufacturers are interested in whether or not 3D printing can replace plastic injection molding – is because (unlike plastic injection molds) 3D printing machines don’t have to be custom made for every part. What this means is that one machine can produce a relatively large amount of differently shaped parts.

With plastic injection molds, only one shape can be made by one mold, and that shape is determined by the mold cavity, of course. For different shapes, you need different molds, and having a plastic injection mold designed and made is rather costly.

This once again shows why manufacturers would be interested in a tool that can be used for any part without having to be specially made. It seems exciting, and like it can open up the world of manufacturing to brand new possibilities that would’ve been too costly in the past.

But how does injection molding really compare to 3D printing? Can manufacturers replace their injection molds with 3D printers now? Are 3D printers the future of manufacturing in the plastic industry?

Injection Molds vs 3D Printers

It’s true that 3D printing is a promising and exciting new development in the manufacturing industry. It’s also true that 3D printing can save manufacturers money when it comes to producing their final products. But currently the 3D printing process is just not sophisticated enough to replace plastic injection molding entirely.

The best use of 3D printing is for prototyping parts. You can save enormous amounts of money by having prototypes produces through 3D printing rather than injection molding while you’re still in the phase of designing a product that you aren’t mass-producing yet. This is especially the case if you only want one or two prototypes.

But apart from helping you save money on producing a small amount of parts for prototyping, 3D printing loses its appeal once you want to mass-produce a part.

The cost per part for 3D printing will be much lower than that of injection molding initially, but the more parts you produce, the smaller the price gap between 3D printing and injection molding will become. Eventually, the price per part will break even, and after that injection molding will once again be cheaper than 3D printing.

The number of parts you can produce before reaching the break-even point where injection molding and 3D printing costs the same per part will depend on the part you want to produce. But it can be surprisingly low sometimes, so you should look into the exact costs before assuming 3D printing will be cheaper.

Injection Molding Benefits

So, the relatively simple process of molding can still be cheaper than using clever computer software and a 3D printer. That comes as little surprise. But plastic injection molding is still superior to 3D printing in many other ways.

For instance, the molding process still has a much faster turnaround than that of printing. Which makes sense, since parts are produced through molding them in one go, rather than one layer at a time.

This is one reason why 3D printing still fails to be practical for mass-production. Compared to injection molding, it is painstakingly slow and you’d need a whole lot of printers to keep up with one single injection mold in terms of parts per hour.

But 3D printing is also less versatile. You’re restricted when it comes to what polymers you can use, so producing certain things through printing is literally still impossible in some cases. Meaning that you might not even be able to use 3D printing as a practical, cost-effective alternative for prototyping some parts.

And lastly, the versatility of injection molding allows you to create products of a higher quality.

So while 3D printing is exciting, it’s still far behind plastic injection molding. The technology will need to be improved to make it faster, more versatile and cost-effective for mass-production before it can realistically be used to manufacture high quality plastic parts. In the meantime, manufacturers should feel free to look into 3D printing for prototyping a small number of parts whenever possible.

Types of Plastic Molding

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Chances are, you’ve seen various videos on YouTube about how different everyday products are made. For a surprisingly large amount of different products, there’s some kind of molding involved in the manufacturing process. Even loaves of bread are baked in bread pans to give them a shape. And most candies – whether chocolate bars or jelly babies – are poured into molds of some sort.

Molding is a quick and convenient way to reproduce the same shape over and over while getting the same result every time. Because if this, it’s the most popular way of producing plastic parts. In the modern world, plastic is all around us. From children’s toys and kitchenware, to vehicles and medical equipment.

With the wide variety of uses plastic has, there are many things to consider during the process of designing parts. Not only will you have to choose the right polymer to ensure optimum part performance, you’ll need to know about different injection molding techniques that will ultimately shape your polymer into a usable plastic part.

How to Design a Plastic Product

Assuming you’re starting from scratch, with nothing but an idea for a plastic product you’d like to create in mind, there are a couple of things you should know about the creation of plastic products:

  • It’s good to have a design on hand for any product you want to make, but ultimately, you’ll have to get engineers and professional designers involved somewhere during the process.
  • 3D printing is a great way to help you create a cost effective prototype of any product you wish to create. Because 3D printing doesn’t require a specially designed mold, it’s easy to use this method without blowing the bank. However, 3D printing fails to be a viable long-term option for part production, as it’s not very versatile and takes much longer.
  • If you need to have a plastic mold specially designed and made in order to produce your product parts, you’re looking at a hefty sum of upfront investment. Plastic molds are very specialized pieces of precision-engineered equipment. That said, a good mold can complete 500,000-2,000,000 cycles in its lifetime, depending on what kind of mold you’re looking at.

With so many plastic products on the market, many people might not realize the sheer amount of work and dedication that goes into designing and creating these products.

With that said, let’s have a look at some of the molding processes used to create plastic parts.

Injection Molding

To explain injection molding simply, it’s the process where molten plastic is injected into a mold, then left to cool. Once the plastic has cooled, the plastic part is ejected and the process is repeated.

Plastic injection molds usually consist of two halves. Think about these halves as two halves of a hollow egg shell – when pressed tightly together, this shell with form a cavity into which the molten plastic can be poured. Obviously the mold won’t have an egg-shaped cavity unless you aren’t trying to mold egg shapes, though. The cavity will be shaped like whatever part is being produced.

Plastic injection molding is incredibly versatile, and is used to produce a large variety of differently shaped parts.

Rotational Molding

Rotational molding is mostly used to create parts that are hollow on the inside.

The process of rotational molding uses centrifugal force to form parts. During the process, liquid or powder-form resin is placed into a mold. The heated mold is then rotated, causing the resin to evenly coat the inside of the mold.

Blow Molding

Things like plastic bottles (like the ones in which soft drinks are often sold) are usually made using the blow molding process.

Like with most other forms of plastic molding, there’s a mold shape that serves as the “shell” of the shape you want to produce. But unlike with injection molding, the plastic isn’t simply injected into the mold. Instead, the plastic blown into the mold shape by filling it with air, much like when you blow up a balloon. As air is blown into the plastic, it takes the shape of the mold it’s blown into.

Compression Molding

With compression molding, the plastic is poured into a mold. Different parts of the mold then compress the plastic so that it’s literally squeezed into shape. This produces strong parts, and so the process is often used in the automotive industry.

Extrusion Molding

The basic concept behind extrusion molding is that the plastic is squeezed into a long cavity to shape it. It’s basically like if you were to squeeze cookie dough into a round, plastic pipe. You’d be left with cookie dough in a long, round cylindrical shape. If the pipe where square, you’d have cookie dough in a long, rectangular kind of shape.

This is the basic concept behind extrusion molding. And so this manufacturing process is used mostly to make long, cylinder-type shapes like pipes, for instance.

Those are just basic explanations of the main processes used to mass produce plastic parts. In some cases, a single plastic product will consist of different parts, and these different parts might be produced using different molding processes.

Tips for Transferring Your Injection Molded Tooling for Manufacturing

Transferring your molds to another merchant to run creation can be an overwhelming undertaking. This can be a muddled, once in a while unnerving choice that can be characteristically pervaded with worry because of the various things and procedures to be considered.

Any potential injection molder needs to demonstrate its money related security as an organization before being picked as the successor in getting your tools and running production. Likewise – be sure beyond a shadow of a doubt your picked infusion decay has a recorded apparatus exchange system.

Tool exchange methodology needs to incorporate each progression the new seller will take to guarantee the smoothest apparatus exchange – one that truly restricts any loss of creation.

How to Safely Support Tool Transfer of Injection Molding Tooling

It’s the duty of your new infusion disintegrate to build up your device exchange group. This group needs to comprise of and be set up by;

  • Agents from every single proper office
  • All staff from building through generation who should be advised of your tooling task to realize what is normal before the instrument touches base at their office

Any applicable data about the apparatuses will be given to the new merchant for legitimate assessment and review of the devices. This data incorporates:

  • Drawings
  • Shape details
  • Part data
  • Generation data
  • Quality data and any required esteem included data or helper gear

Continuously talk about venture courses of events, desires and recurrence of venture updates with your infusion decay right on time in the instrument exchange prepare so you stay on top of it at all circumstances.

Confirm Personalized Service

Your apparatus exchange group ought to work eagerly with a specific end goal to bolster and guarantee brilliant principles for your plastic parts are accomplished. This will incorporate;

  • Plan of Experiment
  • Finish Process Validation
  • Creation Realization Process
  • Approved ERP System
  • FMEA
  • Capacities Studies
  • Improvement of Custom Control Protocols
  • Accomplish dock-to-stock status with customers

Pick an organization with elevated requirements of incredibleness and an unmistakable duty to supportability and worker obligation. These qualities ought to be tied down in the organization’s way of life in a way that keeps them adding to and keeping up a focused industry edge.

Why To Secure Value Expansion and Evaluation for Manufacture-capacity

Keeping up fabricate capacity implies growing your esteem. This happens when the infusion decay legitimately assesses the accompanying:

  • State of the mold
  • Sap choice
  • Part geometry
  • Nature of particulars
  • Clear, reliable documentation

These assessments additionally require forthright arranging, venture, correspondence and clear ID of objectives.

Assessment and Validation of Performance

Approvals are required for successful execution assessment. The execution of FAIR’s and CAP’s assistance with approval, as well as with confirmation of part conformance and determinations.

Creation handle assessment occurs after the approval and before the new disintegrate starts to oversee and deliver the new parts.

Pick Experience for your Tool Transfer – Expert Customized Injection Molding

When you are compelled to do a major switch in assembling – it ought to go so easily you just notice the expansion in quality, meticulousness and opportuneness. Your commanded apparatus exchange ought to be completely effortless.