Investment Casting Shell Quality

Investment casting shell quality is a very important factor in producing top-notch, reliable parts. There are numerous potential causes of less-than-optimal shells that are controllable by the right foundry staff and processes. Shells are made by repeatedly dipping wax patterns in a special ceramic slurry, which is then heated to produce molds for the desired parts. Inferior shells can result in inferior parts. Top-quality shells require careful management of slurry composition, drying time, ambient temperatures, humidity, air flows, and other factors. There are many other quality control considerations in the investment casting process, but shell quality is a good place to start.

Optimize Aluminum Castings

While aluminum is an extraordinarily beneficial alloy for many applications, it takes much expertise and care to optimally produce aluminum castings. During the production process, the foundry staff must ensure that the molten aluminum does not experience degradation through absorption of hydrogen or oxygen, which both increase over time. Creation of undesirable oxides is a real concern, as is transient element losses, impacting levels of calcium, magnesium, strontium and sodium. All of these can compromise the integrity of aluminum castings. Work with a foundry staff that has the expertise and background to ensure the correct handling of aluminum alloys.

Alloy Casting Temperature Requirements

Casting specifications may require specialized alloys that offer highly desirable properties. They may also have widely varying alloy casting temperature requirements. It is very important for your foundry to have the proper equipment and staff expertise to optimally handle a broad range of alloy casting temperatures. For example, aluminum alloys have melting points starting at just above 1,200 degrees F, while nickel’s melting point is approximately 2,650 degrees F. Copper melts at 1,983 degrees F, and temperatures of 3,380 degrees F are required to produce chromium castings. Specialized alloys melting points can differ with their compositions, so it is important to rely on an experienced metallurgist to deliver the highest quality castings.

Die Casting Size Limitations

If you’re a manufacturer considering different options for casting your parts, you should be aware that die casting can offer some beneficial features, but it also has some drawbacks, like size limitations. Typically, die casting can accommodate parts that weigh up to 75 pounds. If this is too limiting for your needs, consider investment casting, which can produce much larger parts, while offering additional advantages. Pennsylvania Precision Cast Parts can produce parts up to approximately 250 pounds, while delivering exceptional quality, reliability, and long-term cost effectiveness.

Zero Days Lead Time Order for Investment Castings

To save time and money, many manufacturers are opting for PPCP’s zero days lead time ordering for investment castings. With this just-in-time delivery service, PPCP makes the pre-arranged number of castings on an established schedule and stocks them in the foundry until needed by the manufacturer. In addition to saving space at the manufacturer’s facility and reducing inventory cost, parts can often be available faster. In addition, invoices are only sent after the castings are shipped. A PPCP professional team member can help you determine if zero days lead time ordering is right for your company.

Heat Treating Investment Castings

To achieve the optimal performance and characteristics of precision cast parts, foundries will often utilize the heat treating of investment castings. In many cases, this is a critical part of the production process. Once the casting has been set, it can be subjected to temperatures of 3,000° F or higher. This alters the molecular structure and the alloy’s properties. Heating combined with either rapid or slow cooling can greatly increase the metal’s structural consistency, strength, ductility, and other critical characteristics. It is important to have an experienced metallurgist directing the heat-treating process.

Investment Casting Charpy Impact Testing

If it is important to determine how ductile or brittle an alloy may be in a finished part, metallurgists often utilize investment casting Charpy impact testing. Charpy impact testing utilizes a pendulum with a precise weight on the end. A notched, standard-size sample of the alloy to be tested is mounted and struck by the weight. The distance the pendulum is drawn back determines the amount of energy that impacts the sample. If more energy is needed to break the sample, it is more ductile. More brittle alloys require less energy to cause a fracture. This very useful test helps ensure high-quality parts that meet manufacturers’ specifications.

Precision Cast Parts with Fusible Alloys

Many manufacturers have discovered that investment casting is an excellent choice for producing precision cast parts with fusible alloys. Such alloys exhibit comparatively low melting points, below 450° F. This, along with other properties like good thermal conductivity, makes them excellent alloys for a wide variety of applications, from fire sprinklers and temperature-relieve devices to complex aerospace components, laboratory equipment, electronic instruments and much more. Tin, lead, bismuth, and other metals are examples of fusible alloys. Some common ones are Field’s metal, Cerrosafe, and Rose’s metal, to name just a few.

Investment Casting Sustainability

In today’s business, scientific and social environment, many manufacturers want to know about investment casting’s sustainability. The good news is that it is quite environmentally friendly, especially compared to many other production processes. The alloys and wax used in investment casting are recyclable, and the near-net-shape process produces little or no waste to be handled. It also saves time, energy and money in many cases. Investment casting is clearly a responsible choice.

Investment Casting or 3D Printing

With the rapid advances in computer printing technology, some manufacturers are asking if they should utilize investment casting or 3D printing to produce their parts. While 3D printing can be an excellent choice for rapid prototyping, it cannot produce parts with the quality and performance of investment casting. It falls short in many areas, from surface finish, porosity, and inconsistency to very limited alloy choices compared to investment casting. Perhaps some day it will be on par with investment casting, but that is a long way off.

5 Key Advantages of Investment Casting

When choosing a process for producing cast parts, consider these five key advantages of investment casting:

  1. Alloy Flexibility – Investment casting can accommodate a much wider range of alloys than many other processes. It can cast everything from common metals like iron, steel and aluminum to highly specialized alloys of diverse compositions.
  2. Intricate Designs – Molten alloys are poured into continuous molds, making it possible to accommodate complex designs with sharp angles and complicated geometries.
  3. Accuracy – Investment casting is a near-net-shape process, which can deliver extremely accurate finished parts. Tolerances down to a tiny fraction of a millimeter are achieved.
  4. Surface Finish – The investment casting process can produce parts with exceptionally fine finishes without much or any post-casting work.
  5. Part Sizes – Investment casting can be used to produce a wide range of parts, from just a few ounces to hundreds of pounds.

These and other benefits make investment casting a great choice for many applications.

Differences Between Investment and Die Casting

While the processes utilize similar manufacturing techniques, there are meaningful differences between investment and die casting. Here are three of them:

  1. Die casting can only be used for non-ferrous metals, while investment casting can be used for both ferrous and non-ferrous alloys.
  2. In investment casting, production dies are single-use ceramic molds that are broken off the casting after cooling. Die casting molds are reusable.
  3. Parts made with investment casting typically require little or no finishing and machining work. Die cast parts usually require post-casting processing.

As a general rule, investment casting is best used when high-precision, complex, top-quality parts are required.

Investment Casting Partner

Moving to a new parts supplier can be a daunting task that seems to take more time and attention than you can spare. That’s why PPCP doesn’t want to be just your parts supplier; we want to be your investment casting partner. What’s the difference? A lot. Our people are experienced, professional, and totally committed to helping you succeed. Our processes have been developed and honed over decades to ensure state-of-the-industry quality and value. And the performance of our company, people, and products are leading the pack. People, process, performance. Read more about it on our PPCP website (link:website home page) and give us a call at 717-273-3338 so we can put our partnership to work.

Investment Casting Technology

While it may sound simple and straightforward on the surface, investment casting technology goes far deeper. When the first craftspeople used nascent investment casting technology five thousand years ago, they had no idea how it would change the world. Through the millennia, advancing technology has dramatically improved the capabilities, performance, and applications of investment casting. From alloy development and process management to non-destructive testing and quality assurance, it keeps getting better and better. Add the skill, experience, and creativity of expert foundry professionals, and investment casting is virtually certain to meet and exceed expectations.

Investment Casting for Small Run

Investment casting offers the best cost per part on long and repeat runs, but in many cases manufacturers have found that investment casting for small runs can also deliver excellent value. While the per-part cost may be a bit higher, the process makes up for it in several ways. It produces extremely accurate, high-quality parts that can perform better than parts from other production methods. As a near-net-shape process, investment casting eliminates or significantly reduces the need for machining and finishing work, saving time and money. Taking into account long-term considerations and indirect costs, investment casting may be just what you need for a short casting run.

Casting Surface Roughness Measurement

If the finish of your precision cast parts is an important consideration, it is critical that your foundry utilizes accurate investment casting surface roughness measurements. Surface roughness is typically measured by Ra, Roughness Average, and RMS, Root Mean Square. Ra calculates the average of the peaks and valleys on the surface of the parts. These are very small and not usually visible to the naked eye. RMS utilizes the root mean squared of the peaks and valleys and reacts more to a small number of bigger peaks (flaws). The best option depends on the part specification requirements.

Investment Casting Integrity

Manufacturers who require high-performance, exceptional quality parts often opt for investment casting integrity. In a wide variety of applications, investment casting out-performs other processes in many ways, ranging from inclusion and porosity to brittle castings and rough finishes. These and other defects can be virtually eliminated by the right foundry, employing expert process management; rigorous quality assurance; and comprehensive, non-invasive testing. If casting integrity is important to you, start by considering the integrity, experience, and track record of your foundry.

Achieve Casting Industry Standards

To be confident your casting partner will deliver the high-quality parts you need, run after run, make sure your foundry achieves casting industry standards. A foundry that specializes in investment casting should follow industry best practices and meet or exceed many standards set by organizations such as ASTM International, American National Standards Institute (ANSI), Aerospace Material Specifications (AMS), American Welding Society (AWS), and more. These standards have been established through decades of experience, study, and testing in production and laboratory settings.

Avoid Common Casting Defects

While investment casting is an excellent process for a near-limitless range of parts and applications, it is vital to work with a foundry that can avoid common casting defects. To consistently produce top-quality investment castings, a foundry must have an up-to-date, well-equipped facility; experienced staff with expertise in metallurgy; and other essential resources. Without these assets, parts can be defective or compromised by poor surface finishes, porosity, distortion, incomplete castings, voids, and more. It is crucial to work with a state-of-the-art industry foundry like PPCP to avoid these issues.

The Right Casting Process

Choosing the right casting process for your parts and applications can make a significant difference in the quality and performance of your components. There are many factors to consider depending on your needs. Following are key items you should take into account:

  • Application – What is the part’s function, and are there special requirements?
  • Mechanical – Will finishing work or assembly be needed?
  • Alloy – Are specialized alloys needed?
  • Precision – Are challenging tolerances and specifications required?
  • Complexity – Is the part design intricate, requiring fine work?
  • Quantity – What are the production runs and frequency?
  • Quality – Are there challenging performance requirements?

Precision Cast Parts from Duplex Alloys

When manufacturers require components with specialized characteristics, a good option is precision cast parts from duplex alloys. A duplex alloy is a combination of ferritic (magnetic) and austenitic (non-magnetic) stainless steels. They are combined in varying proportions to achieve desired characteristics for specific applications. In some cases, other additives are used, as well, impacting the part’s corrosion resistance, strength, weldability, performance at different temperatures, and other properties. PPCP’s expert metallurgists can produce the ideal duplex alloy for your application.

View PPCP’s Robotic Dipping Video

For the large majority of time that investment casting has existed, casting shells have been made by hand utilizing a traditional, age-old process. As new technologies became available, robotic dipping was developed, offering excellent benefits in efficiency and consistency. This automated dipping process makes production faster and can run continuously as long as is necessary. It also achieves very consistent molds and cast parts to meet customer specifications and requirements. View the timelapse YouTube video of PPCP’s robotic dipping system installation and operation at

View PPCP’s Alloys Video

Investment casting can accommodate a wide array of common and specialized alloys, making it an excellent process for a virtually unlimited variety of components and applications. The alloys PPCP utilizes range from carbon steel, copper, nickel, and brass to stainless steel, aluminum, monels, duplex alloys, and many more. The metallurgists and foundry professionals at PPCP ensure the highest quality, most dependable castings from all of its alloys. View PPCP’s YouTube video on alloys at

View PPCP’s Investment Casting Process Video

The investment casting process, also called lost wax process, is thousands of years old. It can be used to make a wide variety of parts weighing just a few ounces to 250 pounds or more. PPCP is a leading investment casting foundry, offering a comprehensive range of alloys, services, and expert assistance. To learn more, view PPCP’s YouTube investment casting process video at

PPCP Value-Added Services

In addition to producing high-quality, precision investment castings, PPCP offers an array of value-added services, including:

  • Machining
  • Rapid Prototyping
  • Passivation
  • Coatings
  • TIG Welding
  • Heat Treating

PPCP’s foundry professional can help you determine which value-added services are right for your specific needs and applications.

PPCP Industry Specialization

While an experienced foundry with expert staff, state-of-the-industry equipment, and the right capabilities can produce investment castings for virtually any industry, PPCP offers the following industry specialization:

  • Chemical Processing
  • Construction Machining
  • Fluid Handling
  • Food and Beverage Processing
  • Material Handling Equipment
  • Medical Equipment
  • Petro-Chemical Processing
  • Pharmaceutical
  • Pneumatic Fasteners
  • Printing Press Equipment
  • Pulp and Paper Processing
  • Sealing
  • Textile

PPCP has special expertise in these industries but is fully capable of producing top-notch investment casting for your industry and applications.

PPCP Investment Casting Production Features

PPCP produces an extremely wide range of precision cast parts utilizing cutting-edge investment casting production features, such as:

  • Flexible Quantities from One to Several Thousand Units
  • On-Time Performance (OTP) Expectations
  • Low Defect Rate Expectations
  • Kanban Delivery Programs
  • Just In Time (JIT) Delivery Programs
  • Stock Programs

These and other services are all part of PPCP’s commitment to being your high-value investment casting partner.

Investment Casting Benefits at PPCP

If you’re new to precision cast parts or are unfamiliar with our company, we’d like to share some facts and information about investment casting benefits at PPCP. Investment casting offers many attractive, valuable characteristics, including:

  • Abrasion Resistant Parts
  • Consistency
  • Corrosion Resistance
  • Design Flexibility
  • Elimination of Material Waste
  • Heat Resistance
  • Heat Treated Parts
  • Low Initial Tooling Costs
  • Tight Tolerances
  • Wear Resistance and more

PPCP’s foundry and investment casting professionals can tell you more.

Investment Casting Requires Less Machining

When considering which manufacturing process to use, it is important to know that investment casting requires less machining than other production methods. The key reason for this is investment casting’s near-net-shape process. The molds that form the molten alloys into cast parts are extremely accurate, resulting in castings that are very close to the manufacturing specifications, often within tolerances. They also produce high-quality finishes. Because of these and other factors, investment castings often require little or no machining and finishing work. That saves time and cost, while improving quality and consistency.

Stainless Steel and Aluminum Casting

Investment casting is an excellent process for both stainless steel and aluminum casting, even though the two alloys are very different. Consider the following properties:

  • Weight vs. Strength – Steel is stronger than aluminum, but it weighs about three times as much. As a result, aluminum is a great option when the strength-weight ratio matters.
  • Workability – Stainless steel is less malleable and more challenging to work with than aluminum.
  • Welding – Aluminum is more difficult to weld than stainless steel.
  • Heat Resistance – Depending on the alloy, stainless steel can withstand significantly higher temperatures than aluminum, which softens at 400 degrees Fahrenheit.
  • Electric Conductivity – Stainless steel is a poor conductor of electricity, while aluminum offers very good conductivity.
  • Cost – Stainless steel is usually more costly than aluminum, but in some applications is well worth the additional expense to get its special properties. 

Is Investment Casting Complex or Simple?

Manufacturers may wonder if the investment casting process is complex or simple. It’s actually both, depending on how you look at it. At a high level, it seems straightforward, and it has been utilized for thousands of years. In fact, investment casting is considered the oldest process of its type. Molds are created from tooling, molten alloys are poured in, the castings then are cooled, broken out of their shells, and finished if necessary. But diving deeper, great expertise and metallurgical knowledge are necessary to get excellent results. Working with numerous specialized alloys and addressing the countless nuances of the process takes experience, resources, and commitment. It’s important to choose the right foundry as your partner.

Investment Casting in the New Year

If you’re looking for a better way to produce your parts, you should consider investment casting in the new year. It’s a great time to take a fresh look at your production process. If you are not currently utilizing investment casting, you may be missing out on its many excellent capabilities and benefits, like exceptional quality, flexibility, surface finishes, minimal alloy waste, and much more. If you are using investment casting, but would like to see better, more cost-effective results, PPCP is ready to help. Have a happy and prosperous new year in 2023.

Merry Christmas and Happy Holidays!

As another year comes to a close, everyone here at PPCP wishes you and your loved ones a Merry Christmas and Happy Holidays! We are very thankful for the opportunity to be your investment casting partner, and we take our commitment to helping you succeed very seriously. We know that the most direct pathway to success, for you and for us, is creating strong, long-term, collaborative relationships. We hope you have a wonderful Christmas, great holiday celebrations, and a safe, prosperous New Year.

What Are Material Surcharges?

A frequently asked question related to PPCP’s investment casting pricing is, “What are material surcharges?” The quick answer is material surcharges are a simple way to address widely varying alloy costs. PPCP divides its casting prices into components that help make the process as transparent and competitive as possible. One component is the cost of actually making the castings, not including the cost of alloys. This expense is essentially the same for all alloys. The other component, the material surcharge, is related to the cost of the specific alloys being used and their market price at that time. PPCP publishes a monthly material surcharge schedule (make link to: [KW1] on its our website to share current alloy pricing.

Investment Casting Tooling

Manufacturers may have a concern about the investment that is required for investment casting tooling. At first glance, it may seem more costly than other processes; however, when taking into account long-term considerations, it is a better investment in many cases. Tooling is the creation of a metal structure that is used to make wax patterns that are the molds that form the final castings. It is true that there may be a larger up-front expenditure for investment casting, but these tools can be used over and over. This spreads the cost over a great many castings, lowering the per part expenditure. When you also consider the many benefits and advantages of investment casting, it is a wise, long-term investment.

Investment Casting or Die Casting

One of the decisions manufacturers may need to make is choosing between Investment Casting and Die Casting. While both have their benefits and applications, investment casting is often the better option. Here’s why:

Long-Term Cost Effectiveness – a smart investment for long and repeat runs

Superior Surface Finishes – can achieve excellent finishes with little or no machining

Exceptional Precision – can accommodate complex designs and geometries

Flexibility – excellent for ferrous and non-ferrous metals, as well as many different alloys

Exacting Tolerances – can meet even the most challenging requirements

These and other characteristics make investment casting the superior choice over die casting in many situations. Foundry professions can help make the final decision.

We Give Thanks for Our Customers

Like most people, the PPCP team will take time during the Thanksgiving break to give thanks for our families, our friends, our health, and our good fortunes. But we also want to give thanks for our wonderful and valued customers. We deeply appreciate your business and the opportunity to work with you year after year. We strive to be much more than simply a supplier to you. We are dedicated to being a partner in success and a high-value resource. Enjoy your Thanksgiving and your time with friends and loved ones.

Ancient & Cutting-Edge Technology

Many people don’t know that investment casting is both an ancient and cutting-edge technology. Also referred to as lost-wax casting, investment casting is one of the oldest metal-forming processes in use today, though we’ve come a long way since it was invented. Evidence of its use dates back 5,000 years for making idols, jewelry, ornaments, and other items. Early investment castings have been found in Pakistan from 4,500 years ago and in Tutankhamun’s tomb in Egypt from before 1,300 B.C. Today’s technology and metallurgical knowledge have greatly improved investment casting, but the basic process remains very similar.

Count on Investment Castings

When manufacturers need vital castings for critical functions, many count on investment castings. Among the many reasons why are:

  • Extraordinary quality
  • Precision and accuracy
  • Reliability
  • Consistency and repeatability
  • Durability

Professionals depend on investment casting in virtually every industry, from medical, precision instruments and food processing to valves and pumps, mining, oil and gas, transportation, military, and so many others. It’s the process they trust.

Sustainable Investment Casting

Manufacturers who want to minimize material waste and care about the environment should consider sustainable investment casting. This near-net-shape process greatly reduces or even eliminates the need for machining and finishing work after the castings come out of the mold. With less cutting and grinding, it produces a smaller amount of waste to dispose of in the environment. It also speeds up production and minimizes subpar parts. Choose investment casting to boost your bottom line and become more sustainable.

Avoid Pitting in Castings

Surface quality of parts is vital to the appearance and often the performance of components, which is why it is important to avoid pitting in castings. Pitting is a commonly occurring problem that can be avoided through careful process management. Contamination in a mold can result in indentations or pits on the surface of the casting. It can also happen when a sprue is poorly designed and allows trapped air bubbles to pit the part’s surface. Such bubbles can also result from overheated alloys, which may create gas in the mold. An under-heated mold can have remanent wax bits from the pattern when it is melted away. An expert foundry staff can avoid these and other pitting issues.

Cure for Inconsistent Castings

While part consistency is essential for the vast majority of manufacturers, all too often they receive more out-of-spec parts than is acceptable. Investment casting can be the cure for inconsistent castings. Investment casting is a near-net-shape process, which means the castings come out of the molds extremely close to the desired geometry and specifications. They require little or no machining and finishing work, which greatly reduces the occurrence of flaws and inconsistencies.

Solution for Discolored, Brittle Castings

When investment castings become brittle and are discolored and rough, it is likely the foundry is experiencing issues that require attention. There could be several possible causes for such problems. The quality of the alloy being used could be substandard or defective. An alloy that is too high in sulfides and oxides could cause the problem, especially when using recycled metal. The issues could also occur if the molten alloy is overheated or if the dewaxing temperature is too high. Experienced foundry staff, including an expert metallurgist, have the expertise, equipment, and resources necessary to address and prevent these problems.

Avoid Casting Defects

Investment casting can produce an extremely broad range of top quality parts, but it requires expertise and care to avoid casting defects. This is because investment casting is far more complex than it appears on the surface. In addition to mastering the science and metallurgy of investment casting, the foundry team must have process expertise and extensive experience to avoid such common defects as poor surface finish, porosity, incomplete casting, distortion, casting voids, and many more. Do your background research and choose your foundry carefully.

Stainless Steel and Aluminum Castings

The investment casting process can be effectively used for both stainless steel and aluminum casting. When choosing the best material for your parts, consider these facts:

  • Strength vs. Weight – Aluminum is not as strong, but approximately one third the weight, giving it an excellent strength-weight ratio.
  • Heat Resistance – Stainless steel has a much higher heat tolerance, which can make it more suitable for certain applications. Aluminum softens at 400 degrees Fahrenheit.
  • Workability – Aluminum is more malleable than stainless steel, which can make it easier to work with and more cost-effective in some cases.
  • Welding – Aluminum is more difficult to weld than stainless steel.
  • Electric Conductivity – Aluminum is an excellent conductor of electricity. Stainless steel is poor.
  • Cost – Stainless steel usually costs more than aluminum but is well worth it for some applications.    

Investment Casting or Metal Injection Molding

When manufacturers are deciding whether to use investment casting or metal injection molding, they often go with investment casting because of the advantages it offers. Investment casting can use a wider variety of alloys and typically achieves better results related to the hardness, density, tensile strength, elongation, and other properties of the finished parts. The near-net-shape process ensures consistent quality and repeatability over very long runs. This significantly reduces the number of out-of-spec and faulty parts, saving time, money, and production hassles.

Investment Casting or Green Sand Casting

If you are giving consideration to both investment casting and green sand casting for your parts, you should know that investment casting offers some important advantages. Green sand casting can be less costly in some cases on a per-part expense basis. Investment casting has the advantage with its ability to handle very complex geometries, deliver better surface finishes, create thinner part walls, and it requires less machining and finishing work. Plus, investment casting can be more economical for long and repeat part runs.

Investment Casting or Sand Casting

When trying to decide whether to use investment casting or sand casting to produce parts, consider the following:

Investment Casting

  • Can produce complex parts, even with very thin walls.
  • Offers the accuracy to achieve precise specifications.
  • Delivers high-quality surface finishes with little or no machining and finishing.
  • Can utilize duplex alloys and both ferrous and non-ferrous metals.
  • Is an economical option over long and repeat runs.

Sand Casting

  • Can be lower cost in some situations, like shorter runs.
  • Can produce very large castings.
  • Also accommodates ferrous and non-ferrous alloys.
  • May be a good option when top quality and precision are not required.

Medical & Pharmaceutical Cast Parts

Investment casting is an ideal process for making a wide range of medical & pharmaceutical parts. Many applications in the medical, dental, and pharmaceutical field require very high quality, exceptional precision, and unwavering consistency. Investment casting’s near-net-shape process can meet even the most demanding requirements and exacting specifications. It can also accommodate numerous specialized alloys, as well as common metals that are utilized in medical, pharmaceutical, and other areas. With virtually no margin for error in these professions, investment casting can be a life saver.

Valves Cast Parts

Valves play a vital role in a near-endless range of components and industries, which is why many manufacturers rely on investment casting to produce their valves’ cast parts. Many valve specifications require complex, extremely precise parts to function properly. Investment casting is able to meet those requirements when other processes cannot. In some cases, they also call for specialized alloys, which investment casting can utilize. It is versatile enough to meet the needs of virtually any application and industry, delivering top quality, dependability, and cost effectiveness.