Material Monday: Polybutylene Terephthalate (PBT)

Material Monday: Polybutylene Terephthalate (PBT)

Brand names: Cycolac, Lustran, Hival

What is PBT?

Polybutylene Terephthalate (PBT) is a semi-crystalline thermoplastic that belongs to the polyester family of polymers. It has several different grades that will allow for reinforcement, filled, impact modification, and flame retardancy. It has excellent mechanical and electrical characteristics, it’s stain-resistant, light, and has exceptional short-term mechanical properties.  With high dielectric strength PBT protects electrical and electronic components. It is highly resistant and guards against leakage and breakdown in power circuitry.

Polybutylene Terephthalate Structure

Polybutylene Terephthalate (PBT)

Polybutylene Terephthalate (PBT) Part – Agriculture

 

Benefits

  • Stain-resistant
  • Lightweight
  • Excellent short-term mechanical properties
  • Can last short term thermal excursions and long-term heat exposure
  • High dielectric strength
  • Block UV radiation, excellent heat aging behavior
  • Chemical resistance

 

Drawbacks

  • High mold shrinkage
  • Poor resistance to hydrolysis (sensitive to hot water)
  • Prone to warping
  • Unreinforced PBT is notch sensitive
  • Low HDT at 60° degree Celsius (140° Fahrenheit)

PBT Polyester (Polybutylene Terepthalate)
– Consumer Products

How can I use it?

PBT can be used for various industries, such as industrial, medical, and consumer fields.

Industrial

Common applications for the industrial market include electrical, electrical components, windshield wiper covers, mirror housings, cowl vents.

Properties of PBT

The polymer displays excellent mechanical and electrical properties. Review the key properties of this polyester material discussed below.

  • It has excellent stain resistant and machining characteristics
  • It enables efficient use of material to reduce weight and cost
  • It delivers excellent short-term mechanical properties, such as high strength, toughness and stiffness as well as good practical impact
  • It provides good creep resistance, dimensional stability and low moisture absorption characteristics

 

 

Elongation at Break 5-300%
Elongation at Yield 3.5-9%
Flexibility (Flexural Modulus) 2-4 GPa
Hardness Rockwell M 70-90
Hardness Shore D 90-95
Stiffness (Flexural Modulus) 2-4 GPa
Strength at Break (Tensile) 40-50 MPa
Toughness (Notched Izod Impact at Room Temperature) 27-999 J/m
Toughness at Low Temperature (Notched Izod Impact at Low Temperature) 27-120 J/m
Young’s Modulus 2-3 GPa
Coefficient of Linear Thermal Expansion 6-10 x 10-5 /°C
Shrinkage 0.5-2.2%
Water Absorption 24 hours 0.1-0.2%

Source: Omnexus

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Material Monday: PC + ABS (ABS + Polycarbonate Alloy)

Material Monday: PC + ABS (ABS + Polycarbonate Alloy)

Brand names: Cycolac, Lustran, Hival

What is ABS + PC?

ABS + PC is an opaque material that is a low-cost alternative to Polycarbonate. This low-temperature material has improved strengths over its ABS counterpart, as well as mechanical and thermal properties. Known

ABS + PC (ABS + Polycarbonate Alloy)

Monitor made with ABS + PC (ABS + Polycarbonate Alloy)

for its toughness and rigidity, it has excellent dimensional stability. Extremely versatile, this material can be modified by the addition of glass fiber,

mineral fillers, and flame retardant. It retains colour exceptionally well so it will work fantastically with any branding your project might need.

 

Benefits

  • Good impact resistance with toughness and rigidity
  • Metal coating with excellent adhesion to ABS
  • Very good indoor light colour stability
  • Excellent processability and appearance
  • Easy Processing
  • Sterilization by gamma, e-beam, and EtO

 

Drawbacks

Medical Part

Medical Part made with PC + ABS

  • Poor solvent resistance
  • Low dielectric strength (not a good insulator)
  • Low continuous service temp. (melts easily)
  • Color shift due to UV exposure or certain sterilization methods

 

How can I use it?

ABS + PC can be used for various industries, such as industrial, medical, and consumer fields.

Industrial

Common applications for the industrial market include automotive exterior and interior components, and electrical housings.

Medical

Common applications for the medical field include housings/covers, monitor bezels, handles, caps, battery enclosures, access panels, and control knobs.

Consumer Products

Common applications for the consumer industry include computers, monitors, and business equipment housings and enclosures.

 

Specs

Tensile Strength Flexural Modulus Impact Strength Max Temp. Chemical Resistance
6400-9150 psi 300,000-400,000 psi 8-12 ft-lb/in notched izod 140°-210° F Poor to Fair

 

Conclusion

This opaque material is easy to process, and tough enough to stand the test of time. It’s a cheaper material than your standard Polycarbonate and can be modified to suit the needs of your product.

Need help with your next project? Let the experts at Xcentric lighten your load. Click below to submit a quote or contact our sales staff with your burning questions at (586) 598-4636 or by email sales@xcentricmold.com.

 

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High-Performance Plastics

High-Performance Plastics

Design Optimization: Increasing Performance Through Substituting High-Performance Plastics For Metal

Key Points:

  • High-performance plastics may allow reduction in
    weight and cost while maintaining mechanical performance
  • Part count reduction may further reduce weight
    and simplify designs
  • Elimination of secondary operations saves time
    and expense
  • Production cost and production rate improvements
    with injection molding
  • The cost of prototyping and tooling for
    injection molding is not prohibitive

Progress often dictates reevaluating fundamental decisions

Design and manufacturing professionals are constantly challenged to improve the performance of their products, whether it be reduction in fuel or energy consumption in transportation applications, comfort in wearable devices, or the efficacy of medical equipment and medical devices.

In the ongoing reevaluation of what can be done to improve product performance, one of the most fundamental questions to ask is, “are we using the optimal material for this application”? 

This is no simple matter since in many instances, entire factories and their related supply chains are literally tied to the material selection of a core component.  Think of cast aluminum induction components for internal combustion engines for example.  However, to improve functional and financial performance in a meaningful way, material choice must frequently be reevaluated objectively.

Material substitutions require careful reflection

Considering the implications of substituting a new material for a product or sub-component noted above, the threshold for an acceptable benefit to cost ratio must be high.  In some applications, the reward is obvious: saving a few kilos in a race car means winning or losing, reducing the time to assemble a product might make it commercially viable or a no-go, improving the ability to sterilize a medical device could accelerate adoption.  In marginal cases, the math becomes more difficult, putting pressure on designers to seek fractional performance gains wherever they can be found.  In many important cases these gains are found in substituting older metal designs for high-performance plastics.

High-performance plastics have many advantages

Although high-performance plastics are no substitution for metal alloys for many applications, there are countless applications where metals cannot perform the role of a polymer.  It is between these two spaces where either a polymer or metal could perform the desired functions at an acceptable manufacturing cost in commercially meaningful volumes.  So, when one looks to achieve a high benefit, cost outcome by transitioning from metal to plastic components, where does one start?

  1. Evaluate a simple material substitution of the component design – Can a meaningful improvement be achieved with an engineering-grade polymer with essentially the same physical / geometrical design?  This is not often the case due to the much different mechanical properties between metals and high-performance plastics, but it may happen where the initial metal design was far from optimal, making a substitution of a lighter and less expensive-to-manufacture plastic component possible.
  2. Evaluate a redesign that takes the advantages of molded plastics into accountPlastic injection-molded components can be very complex at high production rates and low per part costs once the injection molding process has been proven out. This allows the designer to consider reducing part count in assemblies by combining functions into a single component.  This saves weight, production time, additional project logistics, and ultimately cost.  Additionally, molded polymers can incorporate aesthetics via more complex organic shapes and molded-in colors that again reduce secondary operations.  Finally, the wide spectrum of mechanical, physical, and chemical properties of polymers opens many new avenues for clever design not possible with metals.
  3. Evaluate combining the best of both worlds – Polymer components with overmolded inserts can combine the benefits noted above from the use of injection molding and those of metal features in certain critical areas such as threads, embedded wiring, metal tubing for fluid or gas lines, heat dissipation features, or aesthetic elements.     

Once the rudimentary analysis
suggested above is done, the detailed work starts.  From the design perspective, the full
analysis of the static and dynamic performance of the component under the
foreseen environmental conditions must be simulated, tested, and validated.  In parallel, the manufacturing team must plan
the component substitution, estimate tooling, training, and production
validation timelines and capital and operating costs.  Ultimately, the commercial team will merge
the data from the design and manufacturing teams to generate an expected return
on investment (ROI) for the substitution, essentially the mathematical
calculation of the benefit: cost ratio. 

Companies frequently substitute high-performance plastics for metal

Just think about the many products that were once metal that have been replaced by a superior injection-molded plastic component: consumer products, medical devices, sporting goods, and automotive components, all have excellent examples of significant improvement through substituting high-performance plastics for metal. However, there are far more untapped applications that may seem mundane, where the real potential still lies, and the cost of conversion is far lower. 

For example, we have helped clients in the electrical industry convert sheet metal assemblies with multiple fasteners and manual assembly, to sculpted single components that do not require assembly, painting, or electrical insulation. 

The direct per component cost is lower, assembly time is shorter, and the entire manufacturing logistics chain is simplified, all while delivering a superior end product.  This is the power of high-performance plastics.

Actually, incredibly often.  Just think about the many products that were once metal that have been replaced by a superior injection-molded plastic component: consumer products, medical devices, sporting goods, and automotive components, all have excellent examples of significant improvement through substituting high-performance plastics for metal. However, there are far more untapped applications that may seem mundane, where the real potential still lies, and the cost of conversion is far lower. 

For example, we have helped clients in the electrical industry convert sheet metal assemblies with multiple fasteners and manual assembly, to sculpted single components that do not require assembly, painting, or electrical insulation.  The direct per component cost is lower, assembly time is shorter, and the entire manufacturing logistics chain is simplified, all while delivering a superior end product.  This is the power of high-performance plastics.

Injection molding tools, especially for prototypes and short run production, can be very cost effective

Returning to the benefit: cost calculation, the amortization of tooling costs is a big factor in the denominator of the equation.  Even if these costs are capitalized, it is still a cash outlay that must be factored in to project planning when comparing machined, cast, metal injection molded (MIM), or stamped metal parts (to name a few of the most common processes).  For high volume production, the impact of a polymer solution can be dramatic, but even for low volumes due to advanced mold making and molding processes, like those employed at Xcentric, the costs to switch to a plastic component can start to pay off quickly. 

Firstly, Xcentric tooling costs a fraction of that of hardened steel tools and are producing end product literally in a matter of days for simpler projects, and two to three weeks for very complex products.  This accelerates cash generation for the customer and gives early feedback about the viability of the substitute component.  If additional iterations are needed for testing or validation, the lower difficulty of making modifications to the prototype tooling and process parameter changes keep costs under control and the project on track (for more information on project timelines in injection molding click here).  When these factors are combined with the direct and indirect manufacturing gains and end use enhancements, injection molding tools are well worth the investment.

Summary: Substituting high-performance plastics for metals can really pay off

Whether it be increasing the performance of the latest sporting equipment, or making the new kitchen appliance more attractive, or reducing the cost and weight of an aircraft interior component, plastic injection molding has proven endless times that it is a viable substitute for metal in very demanding applications.  So, the next time you and your team is considering methods of improving the performance of your products, consider every area where a plastic component might bring a performance or economic advantage.  You may be surprised that the benefit to cost works out very well indeed.