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Quick Update on Plastic Resin Costs & Plastic Industry to Start 2014

Plastic Resin for Injection Molding Pic


Prices for propylene monomer feedstock fell again in March which may help to drive down cost.     

Weak demand for injection molding of rigid packaging and consumer/institutional products in the past two months may increase availability, stated Frank Esposito in Plastics News article “Polypropylene prices drop in March”.

PP expansion projects are expected to produce new capacity in the upcoming years; this will lead to increased PP exports from North America.   


How to Assemble Plastic Injection Molded Components

Ultrasonic Welding Plastic ComponentsThere are several methods for joining injection molded plastic components but each one has equipment, cost and labor to consider. 

The simplest way to join plastic parts is to design a fastening element such as a hinge or latch into the part.  Stronger plastics are required for these because the joint must survive the repeated use, load and strain of assembly. 

Mechanical Fastening

When working with precision injection molded components, mechanical fasteners like screws, rivets, pins, or nuts tend to be the most common joining methods.   The fasteners can be molded in place, forced, glued or expanded into holes.  They can also be inserted ultrasonically or with heated probes.

Mechanical fasteners require that the plastic use can withstand the strain of fastener insertion along with the high stress around the fastener. 

Threaded fasteners work best on parts with thicker sections.  Thread-forming screws are preferred for softer materials and thread-cutting screws work best on harder plastics.  Push on lock nuts or clips may be suited better for thinner section parts. 

If the fasteners need to be removed a number of times for disassembly because of servicing or replacement, metal inserts are recommended.

Solvent Bonding  

Plastics are softened by coating them with a solvent, then clamping them or pressing them together. The plastic molecules mix together and the parts bond when the solvent evaporates. This process is limited to thermoplastics. 

The amount of pressure used is critical, as too much pressure causes parts to distort.  A day or more at room temperature or several hours at elevated temperatures are also sometimes needed to help cure the bond.

UV Bonding 

This is a process that utilizes ultraviolet curing with high-intensity ultraviolet light to instantly cure or dry inks, coatings or adhesives.  Offering many advantages like increased production speed, reduced rejection rates, and improved scratch and solvent resistance, along with the facilitation of superior bonding.  This method is limited to clear materials.

Tips for Precision Production Machining Outsourcing

Precision Production MachiningPrecision production machining is an important player in the production of high-accuracy and high-quality components.  It is one of the most important techniques used in industries today and used for shaping tools and parts to their highest-possible level of accuracy and tolerance.

This process is capable of handling many types of metals. Different cutters are used based on the material in use such as solid cutters, laser cutters or even water cutters in order to provide the optimum levels of accuracy. 

Steps Need To Be Taken to Protect High-Levels of Accuracy 

When looking for a production machining partner, you need to consider a range of issues beginning with the application.  The OEM should always partner with a vendor who is fully-qualified to work within the required component material. Be sure to consider the vendor’s equipment and level's of expertise. 

For higher standards of intricacy or tighter tolerances, the OEM will need to inquire about the experience levels of the vendor for specific applications or industry-critical requirements. 

To run an advanced production, quality equipment like CMM's which are used to inspect parts for dimensions are needed. Another consideration includes the vendor's ability to provide any pre or post production services like engineering assistance, assembly or packaging that may be required for your project. 

Purpose of Process Validation for Injection Molding

injection molding

Process Validation new definition from the FDA is “the collection and evaluation of data, from the process design phase through production, which establishes evidence that a process is capable of consistently delivering quality products.”   This needs to be performed when the process is not fully verified by inspection or testing.   For injection molding of critical components, this detailed and successful process validation must be defined and approved after producing parts that consistently perform according to customer specifications before production can be begin. 

Before beginning process validation for injection molding, it is important to understand the manufacturing process and the product specifications.   Experimentation by changing process parameters to determine which process variables having more impact on the product as well as how far those process variables can be varied while still manufacturing product that is acceptable and meets customer specifications.    Also, a clear definition of product specifications must be determined using scientific units of measure and defined limits and include industry standards whenever possible. 

There are three elements in the process validation process that play critical role in the injection molding process which are IQ, OQ and PQ.  Each of these elements need to be approved before proceeding to the next element.

What is IQ (Installation Qualification)?

During the first stage, the process equipment, along with supporting and subsystems, are inspected to ensure they conform to the requirements of the manufacturer and are installed appropriately.   

A few factors that are given consideration during IQ include the installation conditions, design features of the equipment, the conditions of the given environment and any documents, illustrations or manuals provided by the supplier.

Once installation and design specifications are met which can repeatedly produce parts that will perform up to standard, the process validation can continue to OQ.

What is OQ (Operational Qualification)?

This stage tests the newly installed equipment to ensure it operates as expected, and gauges the conditions under which it will continue to do so.  Test runs will determine the highest, lowest and nominal operating processes by varying the pressures, temperatures, velocities and other factors from the initial process arrived at during IQ.

Factors considered during OQ include the process control limits, the raw material specifications, the requirements for handling the materials, training and the short term stability and capability.


Understand Cold Runner and Hot Runner Systems for Plastic Injection Molding

Injection Mold Design Guidelines

Cold runner systems are used for plastic injection molding processes. This system cools the material in the channel between the nozzle and the cavity (the runner) and is then ejected along with the part.

These systems offer a simpler and less-expensive alternative to hot runner systems. Cold runner systems offer advantages such as reduced maintenance requirements and rapid color changes.

Understanding Cold Runner System for Plastic Injection Molding

Cold runner systems are used on either two or three plate molds.  Two-plate molds have one parting line along which the mold is split into two halves.  Three-plate molds have two parting lines.  When a part is ejected, the mold splits into three sections. 

Three-plate cold runner plastic injection molding provides for greater design flexibility and allows gates to be installed according to application requirements. Cold runner systems also differ in terms of product specifications and features. 

Regardless of whether the alignment uses two or four pins, or whether the assembly screw orientation for cold runner systems is from the parting line - or from the back side, the obvious disadvantage of this system is the wasted plastic that gets generated. 

The runners are either disposed of - or they are reground and reprocessed with the original material.  This adds steps in the manufacturing process. 

Considerations for Designing Cold Runner Molds

It is important that the cold runner dimension is thicker than the component.  This ensures that molten material can be packed into the component as it cools without any restriction. 

The most efficient and easy to machine cold runner design is the round runner, with each half of the mold containing one half of the runner diameter.  Another runner design is a round trapezoid runner milled either in the core-side or the cavity-side of the tool. 

What is Insert Molding for Plastic Components?

Insert Molding

Insert Molding combines metal and plastics, or multiple combinations of materials and components into a single unit. The process makes use of engineering plastics for improved wear resistance, tensile strength and weight reduction as well as using metallic materials for strength and conductivity.  

The metal inserts and bushings are for reinforcing the mechanical properties of the plastic or thermoplastic elastomer products. Insert molding reduces assembly and labor costs, reduces the size and weight of the part, improves component reliability, and delivers improved part strength and structure with enhanced design flexibility.

Uses For Inserts

A variety of inserts can be molded into plastic components.  These include a diversity of magnets, screws, studs, contacts, clips, pins, surface mount pads, rivets, threaded fastners, bushings, tubes, etc. manufactured in materials such as brass, stainless steel, bronze, aluminum, copper, MonelTM and nickel/nickel alloy.

Insert molded components can be used in housings, instruments, knobs, devices and electrical components for a wide variety of applications in the medical, defense, aerospace, electronics/electrical, industrial and consumer markets.

Advantages of CAE/CAM for Plastic Injection Molding

Injection Molded Part Design

CAE/CAM is a term that means computer-aided engineering/computer-aided manufacturing.  CAE/CAM is an advanced computer system and is commonly used for designing and manufacturing products, many of which are produced through the process of custom plastic injection molding. 

This broad term - CAE/CAM is used to refer to a number of technologies mostly used for modeling and designing products. 

With a CAE/CAM model, engineers can measure real-life attributes, such as volume, density, mass, center of gravity and moment of inertia, measurements for injection molded components or molds that otherwise could only be made on an actual part or mold component.

Benefits Of CAE/CAM Designs

Owning the flexibility for making significant changes to major or minor design very easily - cannot be overstated.  Designers now easily move dimensional changes that save drawings for future use or reference.

Proper utilization of CAE/CAM technology helps designers see their designs in the most realistic ways possible. During design processes, a designer is able to cross-check the functionality of their product. Designers are easily able to identify mistakes in the design while still having plenty of time to modify them before proceeding to the next manufacturing phase. 

New products developed using CAE/CAM software are tested virtually under practical and realistic conditions. This ease of part specification means making changes that facilitate into efficiencies in function for a system of parts - as well as the manufacturing of any specific part. 

Designers for custom plastic injection molding parts can easily create an effective and efficient design more easily than ever before. With the evolution of CAE/CAM software, designers are able to design and draft products faster and faster. This has served to drastically reduce the overall cost of the development of all-new products. 

CAE/CAM software has made it possible for engineers to perform every level of the designing process - including creation, optimization, analysis and modification of the product - totally on the computer. 

A Common Procedure For Delivering CAM/CAE Advantages Today

The basic procedure used to deliver the CAE/CAM advantages to the custom injection molding world are the software packages now available. These software packages are known to be both fast and accurate. 

Plastic Injection Molding Resin Predictions for 2014

Resin Raw Material

Predictions for plastic injection molding resin for the coming year are typically made by studying the market trends for industries that make significant use of nylon, polystyrene, polycarbonate, ABS, polypropylene and polyethylene, respectively.

In a recent article by Frank Esposito published in the Plastics News on November 18, 2013, market experts weighted in on their industry predictions for 2014.

Predictions for Nylon

The improved automotive market is helping drive the increase in demand for both nylon 6 and 6/6 resins.  According to HIS Inc. nylon market analyst Paul Blanchard, in a talk delivered at the Global Plastics Summit held Nov 4-6 in Chicago, demand for nylon 6 will increase by about 3.5 percent from 2013 through 2018 globally. Pricing, however may continue on the down-slide since 2011 and may be flat, to slightly down in 2014.

The higher prices for benzene feedstock were spurred in part by the industry’s switch to lighter natural gas-based feed-stocks. This is expected to put pressure on nylon and other resins for the coming years ahead, according to Blanchard. He also reported that Benzene prices “aren’t expected to come down dramatically.” 

Nylon 6/6 pricing is on pace to be flat to slightly down in 2014 due to the demand for that material. It is expected to be 3.6 percent from 2013-2018, Blanchard stated.   

There has been some recent competition between nylon 6 and 6/6 in some applications.  Polypropylene is also competing with both nylons. PP markers “see some real opportunities where nylon is over specified,” Blanchard said. 

Injection Molding Supply-Chain Helps Companies Succeed

Injection Molding Warehouse

A lot of companies are starting to see their supply-chain as more than just a way to reduce operational costs and promote efficiency.  They’re beginning to see how a high-performing supply-chain can not only reduce cost - but also drive revenue growth and competitive advantage for the OEM.

This helps launch new products on schedule while ramping-up production quickly.  In turn, product manufactures are realizing communicative, collaborative relationships with their suppliers are critical to their success.

Injection molding companies know that loyal suppliers are more likely to provide preferential levels of service to them at times - most significantly when materials or components are in short supply.  

Companies want to align themselves with injection molders who strive to be leaders in providing competitive solutions in the areas of cost, quality and delivery.  

Product manufacturers are not created equally; they range from very small companies to very large corporations.  Consequently, their aspirations, needs, logistics and capabilities vary widely. This means that the most important criteria for one - might not be for another.

Supply-chain excellence supports value-creation and competitive-advantage.  It also helps companies launch new products on schedule, ramp up production and expand business in new and existing markets. 

According to an annual global survey of 1,400 executives - the supply-chain is understood as an equally important part of business success - just as much as sales and marketing or R&D product development.  

According to survey participants this happens due to the ability to enhance customer service - which works well as a strong driver of customer loyalty and repeat purchases.  

There are choices everywhere that customers don’t have time to evaluate. They make their decisions based on how they are being served and responded to. 

Suppliers play an important role in maintaining the brand of their customers.  Their responsibilities have evolved, and there is a clear understanding that they are now expected to create value for their customers.

Be Flexible:

  • Flexibility – understand the needs of the customer and adjust to whatever we need to adjust to meet their needs. 
  • Flexibility means adapting a schedule to meet a customer’s needs, bringing in a new piece of equipment to meet a customer’s changing requirements. 
  • How fast can the supply-chain detect and respond to issues i.e.; the truck is late, demand suddenly surges, special packaging or handling needs arise. 
  • How fast can your supplier change to overall company strategies or market place changes…and how fast can your supplier adapt and do what it needs to do to accommodate these changes. 

~ Clearly flexibility ultimately brings in ERP and other software as these can be enablers for flexibility.

The Value of Swiss Screw Machining for Precision Components

Swiss screw machining

CNC Swiss-type automatic lathes are more powerful than ever - while retaining the fast-cycle times with the same flexibility that makes them a standard for most precision, high-production applications.

Today even more tools and greater options are available. Sophisticated controls usher streamlining into the machining process. Swiss screw machining is always preferred for the longer, more slender turned parts, widely used for smaller, highly complex parts and works well for the pieces that have no turned surfaces at all.

Conventional lathes have a fixed headstock. The workpiece itself is held in a chuck or collet. It extends into the machine enclosure working as a cantilever. It can also be supported on the end - by the tail-stock.  

To distinguish a Swiss machine from others in its class - observe it's headstock move. A bar-stock passes through a chucking collet in the headstock - which clamps onto it.

Why Swiss Screw Machining So Valuable?

Swiss screw machining means that the bar emerges into the tooling area through a guide-bushing which locates the bar radially during machining. 

The headstock then moves very precisely back-and-forth in the z-direction - taking the bar with it.  The turning-tools carried on gang-slides contact the bar very close to the guide bushing.

The bar motion provides feed for this cutting action. Gang-slides carry holders for fixed single-point or other tools and may support live-tooling.  Many machines have a secondary spindle back, working tool stations and sometimes one or more turrets that carry more tools as well.

The purpose of supporting the workpiece with the guide bushing is to maintain precision throughout the machine workpiece. 

Any physical object subjected to a force - will deflect. On conventional lathes, if the cutting forces cause too great a deflection - the accuracy of the cut suffers.   If you hold a workpiece securely at one end - then push sideways on the unsupported end - the workpiece bends a certain amount.   Push with the same force on a longer workpiece - it will bend more. 

With Swiss screw machining - the guide bushing supports the workpiece so close to the tools - that the deflection due to the cutting force is essentially zero.  The result means you can take heavy cuts and still maintain precise dimensions on the part.

Swiss turning is used to make small, slender, complex and precision components.  This is possible due to unique design.  In the Swiss turning machine - the bar-stock material is gripped tightly and advanced by the sliding headstock through a guide bushing to the machining section. 

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