Polycarbonate vs Acrylic: Everything You Need To Know About Machining Plastic Materials

Polycarbonate and acrylic are among the most selected plastic materials when it comes to machining projects. Each of them offer different qualities and advantages which make them applicable for different industries within manufacturing, construction, and product design. However, knowing the basic distinctions between the two types of plastics is critical in understanding which one best suits your purpose. This technical document provides a comparison of polycarbonate and acrylic thorough their characteristics, machinability, applications, and performance under various conditions. If you are an aspiring or professional machinist, this article is here to assist you pick the right material for the next project.

What is the Difference Between Polycarbonate and Acrylic?

Polycarbonate and acrylic differ in several ways including impacts, light transmission, and physical manipulation. Polycarbonate has substantial resistance to breaking and is more durable than other plastics; therefore, it is ideal for bullet-proof windows and safes. Acrylic has the highest transmittance of any uncoated plastic, is more scratch resistant, and has a higher resistance to UV damage than poly, so it is more suited for showcases and outdoor signs than polycarbonate. In terms of workability, polycarbonate is more flexible than acrylic, which makes it desirable for machining since it is less likely to break. Acrylic plastics, however, are more preferable for turning and polishing to a fine finish. Even though both materials are highly usable and light in weight, the unique characteristics of each material will aid in deciding which would best serve your purpose.

Polycarbonate and Acrylic: Material Features

The material properties of polycarbonate and acrylic geometric are very different and each serves a different purpose depending on its use. Polycarbonate plastic is used more often than acrylic because it has an impact resistance and strength that is approximately 250 times greater than that of glass and around 30 times higher than acrylic. Polymers with such extraordinary properties are essential for safety-proofing as protective barriers and guards for machines. It also provides high thermal resistance without deformation up to 240 °F (115 °C). On the other hand, acrylic has 92% of light transmission as compared to polycarbonate’s 88%, and that gives it superiority in optical clarity for acrylic signs and high visibility display enclosures. Polycarbonate is more expensive, heavier, and far more durable than acrylic, but acrylic is cheaper and lighter. However, if acrylic is not treated with scratch resistant coating it is more prone to scratches. Both these materials have their own unique versatility; however, all forms of environmental exposure such as UV rays and chemicals are factors to consider when determining which material stands stronger regarding durability, optics, and cost.

Examining Impact Resistance in Contrast to Scratch Resistance

Significantly, both acrylic and polycarbonate differ in their impact resistance, which is critical for the selection of a material. While polycarbonate is over 200 times stronger than conventional glass, making it the material of choice for protective barriers and machine guards, its impact strength makes it stronger than any other type of plastic. Stretching the definition of impact strength, acrylic is around ten times stronger than glass, making it ideal in other circumstances, but still worse than polycarbonate.

When reviewing scratch resistances, acrylic tends to out perform simply due to its superior hardiness in its natural state. On the other hand, polycarbonate can be enhanced with special hard coats, enabling it to undergo a massive increase in its scratch resistance. For instance, polycarbonate that is scratch resistant can have pencil hardness ratings of 3H or above while untreated polycarbonate would simply fall under 1H.

Because of the information provided, it is extremely important to highlight the considerations that need to be made with regards to the application of the materials. In regions where there is need of extreme impact resistance, polycarbonate is the clear winner. However, in places where surface durability is essential, treated acrylic or even coated polycarbonate would suit the situation.

Polycarbonate vs Acrylic: Which is Easier to Machine

When comparing the machining abilities of polycarbonate and acrylic, there are several important factors that should be considered. Here is a deeper analysis of the machinability of the two materials:

Cutting Speed:

Polycarbonate: Requires slower cutting speeds to prevent softening of the material on account of heat.

Acrylic: Tolerates higher cutting speeds when adequately cooled, thus reducing potential for cracking the material.

Tool Wear:

Polycarbonate: Generates moderate tool wear based on its toughness and elasticity.

Acrylic: Generating less tool wear, it is more suitable for prolonged machining operations.

Edge Finishing:

Polycarbonate: Edges are easily finished and leashed, however, additional polishing may be required in order to eliminate fogginess due to machining.

Acrylic: Allows to attain ultimate edge polishing of high optical quality with less difficulty.

Chip Removal:

Polycarbonate: Generates long stringy chips which require effective removal mechanisms to prevent obstruction.

Acrylic: Generates smaller and more brittle chips which are easier to deal with when machining.

Thermal Sensitivity:

Polycarbonate: Has a lower softening point and thus accompanied with poor heat management, there is an increased risk of localised melting.

Acrylic is more resilient to heating during machining, however, the brittleness may mean that lower tool pressure needs to be exercised.

This comparison highlights the essence of choosing the right material and machining parameters as per the set operational goals and expectations.

How to Machine Polycarbonate and Acrylic?

Machining Techniques for Polycarbonate Using Computer Numerical Control

There are special parameters to look out for during polycarbonate machining that ensure the best results and outcomes are achieved when CNC machining polycarbonate.

• For milling, the cutting speed, as a rule of thumb, should be set between 15000 and 20000 RPM.
• For enhanced precision and to mitigate any form of distortion caused by heat, a feed rate of around 150 to 250 IPM is ideal.
• Ensure the used tools have carbide or diamond edges. These materials maintain sharp edges and are durable.
• Use drill bits with a gable point angle of 90-110 degrees which will ensure cracks do not form on the work piece during drilling.
• Localized melting is prevented and heat buildup is suppressed by air or water based coolants.
• Clean surfaces may be hard to achieve with gunky residues from heavy lubrication. Avoid applying too much coolant.

Clamping and Orientation of the Material

• Vacuum tables or soft clamps help in eliminating stress points during machining.
• Prior to machining, ensure the workpiece is held at room temperature for internal stress minimization.
• To tackle overheating and deformation, the depth of the cut for detailed work cannot exceed 0.030 to 0.040 inches.

The fingers of CNC machines can only achieve the desired finishes and maintain the integrity of the polycarbonate covering if adequate tolerances are observed.

Tips In Respect To Acrylic Machining Efficiently

Acrylic machining necessitates proper lubrication to minimize friction and overheating that could otherwise result in cracking or surface defects. To this end, water-soluble coolants are ideal as they not only offer adequate cooling but also inhibit the chemical breakdown of the material. Remember to apply sufficient amounts of lubrication throughout the entirety of the process so as to maximize cuts and alleviate tool wear.

Even though acrylic and polycarbonate are both termed thermoplastics, they differ in some characteristics that will affect the way they perform during machining. Owing to its higher rigidity, acrylic is estimated to have a tensile strength of around 8,000-11,000 psi, making it more susceptible to cracking under high stress. Whereas, polycarbonate is estimated to have a tensile strength of around 9,500-10,500 psi, and a higher impact resistance which also translates to a higher elongation at break of approximately 120%-150% compared to acrylic’s 2%-5%. This means that polycarbonate is much more flexible than acrylic making it less brittle and less prone to chipping during cutting, but it also poses problems such as material deformation if proper heat management is not put in place.

Such differences are even further compounded by the thermal properties. Acrylic and polycarbonate are both plastics, but acrylic begins to soften at the much lower temperature of 105 degrees Celsius than the 150 degrees Celsius of polycarbonate. This means that deeper consideration has to be given to the specific feed rates, cutting speeds, and cooling methods set for each of these materials. For example, cutting acrylic is done at very low speeds of up to 2,500 feet/min, while polycarbonate can be machined at speeds of up to 3,500 feet/min, provided the parts are properly cooled to avoid thermal distortion.

What Are the Best Options for Acrylic and Polycarbonate in Machining Projects?

Cast Acrylic vs Extruded Acrylic: Key Differences

When it comes to selecting the right acrylic for any machining project, one important factor to keep in mind are the varying characteristics of cast and extruded types of acrylic. Let us explore their differences in greater detail:

Production Process:

Cast Acrylic: One of the most durable types of acrylic, cast acrylic is created by pouring liquid acrylic into a mold, where it hardens.

Extruded Acrylic: A more geberal type of acrylic, it is less durable than cast acrylic but has consistent thickness. Because of these properties it is created by a continuous extrusion process.

Machinability:

Cast Acrylic: Has exceptional machinability and has a decreased likelihood of chipping or cracking while being cut.

Extruded Acrylic: Much easier to cut while machining, but is more likely to produce burrs and therefore needs extra polishing.

Optical Clarity:

Cast Acrylic: Very low amount of internal stress and superior optical clarity makes this type perfect for high end optical usage.

Extruded Acrylic: Slightly lesser optical clarity because the production process creates internal stresses on the acrylic.

Surface Quality:

Cast Acrylic: Possesses a smoother surface finish which makes it resistant to scratches.

Extruded Acrylic: Alongside being more cost-efficient, extruded acrylic also has minor surface imperfections which can be altered by polishing.

Cost:

Cast Acrylic: Complex to produce which directly increases the cost.

Extruded Acrylic: Cost-efficient and perfect for projects that are budget sensitive.

Thermal Stability:

Cast Acrylic: Better resistant to thermal stress during machining or use which makes it suitable in varying temperatures.

Extruded Acrylic: Much easier to distort when subjected too high temperatures.

Applications:

Cast Acrylic: Optimal for high precision and visibility applications such as signage and aquariums.

Extruded Acrylic: Used primarily for affordable light weight frames, retail exhibit cases, and lightboxes.

The selection of either type of acrylic will depend on the unique requirements of the machining project. Both cast and extruded acrylic have their merits.

When to Use Polycarbonate Sheet in Your Projects

Polycarbonate sheets are one of the most versatile, durable materials with high impact resistance. Following are some of their properties and data that show their advantages:

• Impact Resistance: Polycarbonate sheets displays impact resistance of 250 and 30 times when compared to acrylic and glass respectively.
• Transparency: Polycarbonate sheets transmit approximately 88-90% of light, offering comparable clarity to glass while being robust.
• Thermal Resistance: The material can withstand temperatures ranging from –40 degrees Fahrenheit to 240 degrees Fahrenheit.
• Flame Retardance: Polycarbonate sheets normally achieve flame ratings of UL 94 V-0 or UL 94 V-2, obtaining reliable fire resistance.
• UV Protection: Many of these sheets come with UV resistant coatings that prevent discoloration, degradation, and increase the overall life span.

These properties enable polycarbonate sheets to be used in safety glazing, machine guards, greenhouse panels, protective shields, as well as automotive parts. They are capable of maintaining dependable functionality in different settings due to their unique combination of strength, transparency, and thermal resistance.

Assessing Acrylic and Polycarbonate Parts for Particular Tasks

A wide variety of factors should be taken into account when assessing acrylic and polycarbonate parts in order to ensure best performance at minimum cost for given applications. Acrylic has the highest optical clarity as well as superior resistance to UV light, and is therefore a material of choice for display cases, signs, and other decorative items. It is cheaper and lighter than glass but more vulnerable to impact.

In other respects, polycarbonate proves to be useful for high impact applications, being up to 250 times stronger than glass. It is the material of choice for impact protective equipment, security glazing, and industrial safety shields. Moreover, polycarbonate’s greater thermal resistance, compared to acrylic, enables it well to withstands the rigors of high temperature environments without loss of structural integrity. This comes at a cost of higher price range and greater scratch susceptibility unless treated.

It is left to the user’s discretion to choose materials as desired based on the materials optical properties, strength, environmental endurance, and budget.

Can Polycarbonate Be Machined Like Acrylic?

 

The polycarbonate machining process – An Overview

Indeed, polycarbonate is machined much like acrylic but major differences must be understood owing to physical differences. Polycarbonate can be construed as somewhat more plastic than other materials which reduces chances of cracking while cutting but makes it prone to deformation under excessive force or heat. During the process of polycarbonate machining, it is very important to utilize sharp and high quality tools so as to lessen stress points.

To prevent excessive heat build up, polycarbonate machining operations like cutting, drilling, or milling should be performed at moderate speeds with adequate water and oil cooling supplied. Large amounts of heat can soften polycarbonate to the degree that it dials down dimensional accuracy and tolerances. Mixtures of water, air, or oil and other coolants are used to regulate the temperature of the machine. Moreover, doors may be opened for the possibility of annealing while using polycarbonate for precise components after the machining process because it alleviates internal stress and enhances the durability of the piece.

Evaluating the Machining Properties of Acrylic and Polycarbonate: Advantages and Disadvantage

Both acrylic and polycarbonate have a distinct setup when it comes to machining, which can be both beneficial and detrimental depending on what it’s applied to. Acrylic is better known for having superior optical clarity and more rigidity and with that comes cleaner cuts and smooth edges. This makes acrylic more suitable for visual or decorative applications. Nonetheless, this specific material is much more brittle than polycarbonate, increasing the possibility of cracking or chipping during high stress machining.

However, polycarbonate has distinct advantages in terms of general durability and impact resistance, which makes it prefered over other materials for structural or load bearing components. Its relatively softer qualities easier allow for cutting and drilling, however such qualities do have a disadvantage since it also makes it more prone to heat or stress deformation during machining. In the end, the decision on which material to use boils down to the specific requirements of the project, for instance, whether appearance, structural integrity, or ease of machining is prioritized.

Special Considerations for Polycarbonate Machining

It is important to consider the deformation caused by the heat when machining polycarbonate. The following data and tips should be observed:

Cutting Speeds: Most powerful ranges vary between 1000-4000 which are ideal depending on the tool diameter. Usage of higher spindle speeds, approximately 4000RPM or more, can lead to melting of edges or warping of surfaces.

Feed Rates: To avoid material stress, feed rates of 100-300 inches per minute are recommended as this will allow cutting to be done smoothly.

Tool Selection: Usual wear and tear on tools can be reduced with mist and air coolers, for around tooled saddles, self-sustaining with sufficient wedges to lower overheating. Keep in mind to use only sharp’s tools while working on plastics; cuts should be cleaner.

Coolant Use: Use of water-based coolants should be avoided, as these tend to degrade or crack surfaces. During machining, it is best to use a mist and air cooler to dissipate heat effectively.

Thickness Tolerances: Polymer’s thermal expansion is sensitive and changes in temperature can cause some dimensional variations with components.

All factors considered, having these guidelines can enhance the degree of polycarbonate amenable for an array of high-end applications while maintaining a structure that keeps precision and strength intact.

What Are the Differences Between Polycarbonate and Acrylic in Terms of Applications?

 

Applications Where Acrylic Is More Economice

Acrylic is the medium of choice for processes in which visual appearance is paramount because it has the best clarity and the most glass-like look and exceptional weathering properties. This makes it ideal for signage, display cases, picture frames and decorative pieces. Furthermore, acrylic is also lightweight and inexpensive, which makes it appropriate for projects with financial restrictions or for locations where mobility is a must. On the other hand, it is not as impact resistant as polycarbonate, which inhibits its use in high-stress or safety-critical situations.

Reasons Why Polycarbonate Exhibits Impact Persistance

Polycarbonate is widely recognized as solid in comparison to acrylic for its high impact resistance properties making it the material used for high-stress and safety critical applications. Polycarbonate can absorb impact forces of 250 times higher than that of glass and 30 times higher than acrylic. The reason for this incredible durability is as a result of its high molecular structure which allows it to absorb and move energy without breaking or shattering. Because of these, polycarbonate is commonly found in bulletproof glass, safety goggles, machine guards or riot shields. Moreover, its high tolerance to extreme temperatures in combination with-furthermore, its attack from ultraviolet light make its outdoor and industry application even better because they do not change their properties when highly stressed and still endure the environmental around them.

Picking the Right Glass Substitute is an Important Step

It is important to match the functions of an application to the right glass alternative. For instance, polycarbonate is the best glass substitute for high impact situations because of its strength and stress resistance. On the other hand, if the most important concern is optical clarity such as with certain lenses, acrylic might be the solution due to its good transparency and smoke-grade scratch resistance. There are other parameters like UV resistance, weight, and cost, wherepol dubious choices may be made which may in turn filter through to the application.

Frequently Asked Questions (FAQs)

Q: What is the major difference between acrylic and polycarbonate when it comes to machining?

A: Acrylic and polycarbonate differ when machining in a single aspect which includes their attributes and how easy it is to work with them. Most commonly, acrylic which is popularly called PMMA is more fragile and therefore when it comes to machining, it should be done with extreme care to avoid fractures. On the other hand, polycarbonate can withstand an impact much better and is easier to work with in terms of machining without fracturing.

Q: What is the characteristic difference of CNC machining in comparison of acrylic sheets to machining of polycarbonate sheets?

A: Both kinds of sheets are possible to be processed through CNC. Loser grades of accuracy are acceptable for polycarbonate sheets, but for akrylic sheets, CNC machining needs to be more careful because brittle nature of acrylic demands much more attention than polycarbonate. In comparison, plastic sheets are much stronger than acrylic and thus will not break or get damaged through CNC machining.

Q: Is acrylic a suitable replacement to glass for purposes of machining in an industry or household setting?

A: Indeed, because of its clarity, acrylic is favored as a substitute glass. It is the material of choice when one needs to be able to see through something and is also more cost effective compared to glass because of how easy it is to cut and shape.

Q: Out of acrylic and polycarbonate, which one has higher impact resistance?

A: Polycarbonate has much greater impact resistance than acrylic. This compound is therefore used in the manufacture of bulletproof windows and in all other cases where strength is essential.

Q: Is there certain use of acrylic that polycarbonate cannot serve?

A: Acrylic is used in instances when high clarity and gloss are required, including signage and display boxes. Acrylic allows considerable light to pass through and is used for decorative reasons.

Q: What are the advantages of polycarbonate over acrylic in machining?

A: Polycarbonate is preferred where high impact resistance is required. Polycarbonate is stronger than acrylic and can withstand higher temperatures. Due to these attributes, it is a preferred plastic in highly demanding applications.

Q: What are the advantages of acrylic and polycarbonate in relation to the manufacturing industry?

A: Acrylic and polycarbonate are popular materials due to their broad useful range, low density and good transperancy. They can easily be machined as compared to glass and possess weather resistant as well as strong properties which can be modified for a specific application.

Q: How does the cost of machining acrylic material compare to polycarbonate?

A: Depending on the scope and miselanes of the project, machining costs can differ. In most cases, acrylic is cheaper than polycarbonate. But, with polycarbonate’s inexpensive prices comes the requirement for careful handling, and with acrylic, there is the need to be sensitive during machining owing to the chance of it cracking.

Q: Are both acrylic and polycarbonate suitable materials for outdoor applications?

A: Both materials can be used outdoors. Acrylic can withstand UV rays and weather elements making it good for outdoor use. Polycarbonate can also withstand environmental factors and offers greater impact strength. Its superior strength makes it useful in more strenuous outdoor applications.

Reference Sources

1. Experimental Investigations on Ultra-Precision Machining of Polycarbonate and Related Issues

• Authors: V. Mishra et al.
• Publication Date: 2020-10-05
• Journal: Journal of Micromanufacturing
• Summary: This study focuses on the ultra-precision machining of polycarbonate (PC), which is increasingly used for optical components due to its lightweight and cost-effectiveness. The research highlights the challenges faced during the machining process to achieve high surface quality and dimensional accuracy.
• Methodology: The authors conducted experiments to analyze the effects of various machining parameters, including cutting temperature and vacuum clamping, on the surface quality of PC components. The results indicated that optimizing these parameters is crucial for achieving a surface finish of Ra 18.1 nm and profile accuracies of 0.116 µm(Mishra et al., 2020, pp. 61–73).

2. A Combined RSM – FEM Analysis of Weld Quality in Laser Transmission Welding of Plastics

• Authors: Nitesh Kumar et al.
• Publication Date: 2024-11-21
• Journal: Materials Research Express
• Summary: This paper explores the laser transmission welding of acrylic and polycarbonate, focusing on the weld quality achieved through various process parameters. The study provides insights into the differences in welding behavior between these two materials.
• Methodology: The authors employed a hybrid approach combining Response Surface Methodology (RSM) and Finite Element Method (FEM) to analyze the effects of laser power, frequency, and scanning speed on weld quality. The results showed significant variations in weld width and heat-affected zone (HAZ) between acrylic and polycarbonate(Kumar et al., 2024).

3. Selection of Process Parameters for Optimizing the Weld Strength in Laser Transmission Welding of Acrylics

• Authors: B. Acherjee et al.
• Publication Date: 2010-10-01 (not within the last five years but relevant)
• Journal: Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture
• Summary: This study investigates the optimization of laser transmission welding parameters specifically for acrylic materials, providing a comparative perspective on how these parameters might differ when applied to polycarbonate.
• Methodology: The authors used the Taguchi method to design experiments aimed at maximizing weld strength. The study analyzed the effects of various welding parameters on the quality of the welds produced(Acherjee et al., 2010, pp. 1529–1536).

       Polycarbonate

       Machining