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29+ years in pharmaceutical machinery, covering capsule filling, tablet pressing, blister packaging, tablet and capsule counting, cartoning, GMP production, and overseas machine service.
In pharmaceutical packaging, machine materials are more than a matter of equipment design. They can directly affect regulatory compliance, product safety, and long-term performance.
Common materials such as 304 stainless steel, 316/316L stainless steel, aluminum alloy, and PTFE each offer different properties and are used for different machine components. But selecting the right material is only the first step. Manufacturers also need reliable ways to verify that the material actually used matches the specified grade.
So, how should these materials be tested beyond simply checking certificates? This article explains the role of common machine materials, practical testing methods and how buyers can verify material quality when selecting and inspecting pharmaceutical packaging machines.
Machine material selection is not simply a matter of making a pharmaceutical packaging machine strong, durable, or visually attractive. It can affect regulatory compliance, product-contact safety, and long-term production reliability.
One of the most important reasons to pay attention to machine materials is regulatory compliance. Pharmaceutical manufacturers operate under different laws, regulations, and GMP requirements depending on their region and target market.
For example, pharmaceutical manufacturing in the United States is subject to FDA CGMP requirements, including requirements concerning equipment construction and product-contact surfaces. In the European Union, GMP requirements are set out in EudraLex Volume 4, which includes dedicated requirements for premises and equipment.
Particularly, for product-contact surfaces, regulators are particularly concerned about whether the material could:
Therefore, when selecting a pharmaceutical packaging machine, buyers should not simply ask, "Is the machine made of stainless steel?" More meaningful questions are “What material is used for each critical component, why was it selected, and is it suitable for the product and regulatory requirements of my region?”
A pharmaceutical packaging machine usually contains many different components, and they do not all need to be made from the same material. Material selection should be based on contact with the product, mechanical function, operating environment, temperature, friction, and chemical exposure.
Product-contact components
As for product-contact components, machine materials generally require good corrosion resistance, cleanability, chemical compatibility, and low contamination risk.
Typical examples include:
|
Machine |
Main Product-Contact Components |
|
Capsule Filling Machine |
Powder hopper, dosing disc, powder filling channel, powder transfer components |
|
Tablet Press Machine |
Hopper, force feeder, dies, punches, discharge chute |
|
Blister Packing Machine |
Feeding system, guide rails |
|
Tablet Capsule Counting Machine |
Product hopper, vibratory channels, counting tracks, discharge chute |
304 stainless steel may be suitable for many general applications, while 316/316L stainless steel is often selected where greater corrosion resistance or more demanding product-contact conditions are involved.
316 Stainless Steal Discharging Chute of Rich Packing’s Desktop Counting Machine
Non-product-contact structural components
Machine frames, external covers, brackets, and protective structures do not normally have direct contact with the pharmaceutical product. Their material selection can focus more heavily on mechanical strength, structural stability, weight, cost and appearance. Generally, 304 stainless steel and aluminum alloy are good choices.
Components for special or demanding materials
Some products create additional machine material-selection challenges. Sticky powders, corrosive formulations, abrasive materials, or products that are sensitive to contamination may require specific material combinations or surface treatments. For example, when it comes to sticky materials in capsule filling, PTFE-coated filling rods are utilized to ensure powder dosing accuracy.
Rich Packing’s Customized Filling Rods for Capsule Filler
Different machine components have different material requirements depending on their function and contact with pharmaceutical products. The following are four commonly used materials and their key characteristics and applications.
Due to the corrosion resistance, mechanical strength, and cost, 304 stainless steel is one of the most widely used stainless steels in pharmaceutical machinery. Its corrosion resistance makes it much more suitable for pharmaceutical equipment than ordinary carbon steel. Its smooth, cleanable surfaces can also support hygienic equipment design.
In pharmaceutical packaging machines, 304 stainless steel is commonly used for machine frames, external housings, protective covers, conveying components, and selected product-contact parts where the operating conditions do not require the additional corrosion resistance of 316/316L.
However, 304 should not automatically be regarded as the best material for every product-contact application. Certain pharmaceutical materials, cleaning agents, or environments can impose more demanding corrosion-resistance requirements. In such cases, 316/316L may be a more appropriate choice.
316/316L stainless steel is generally selected when higher corrosion resistance is required. The presence of molybdenum (Mo) in the alloy makes it difference from 304. Molybdenum contributes to improved resistance in certain corrosive environments, which is one reason 316-series stainless steel is frequently considered for demanding product-contact applications.
The distinction between 316 and 316L is also important. The "L" indicates lower carbon content. This becomes particularly relevant for welded components because lower carbon content can reduce the risk of certain forms of corrosion associated with welding. For this reason, a machine may use 316L for a fabricated product-contact component even when other non-contact structural components use 304.
Aluminum alloy is primarily valuable in pharmaceutical packaging machines because of its low weight and good strength-to-weight ratio. It can be found in machine frames, protective structures, certain moving components and lightweight machine modules.
Compared with stainless steel, aluminum can significantly reduce the weight of a machine component. This can be particularly useful for modular equipment, moving mechanisms, adjustable structures, and machines where ease of installation or movement is important.
However, aluminum alloy should not simply replace stainless steel wherever possible. It is generally more useful for structural and lightweight components than as a universal choice for product-contact surfaces.
PTFE, or polytetrafluoroethylene, is an engineering fluoropolymer with properties that make it useful for specific components rather than large structural parts. In pharmaceutical packaging machines, PTFE can be used for sliding components, sealing components, anti-stick components, and selected material-contact parts.
Its most important advantages include low friction, chemical resistance, non-stick behavior, and good temperature resistance. For example, where a material tends to stick to a metal surface, a PTFE component or surface may help reduce adhesion. Its low friction can also be useful in guiding and sliding mechanisms where repeated movement occurs.
A material with excellent chemical resistance is not automatically the best choice for every high-load or high-wear application. For pharmaceutical machinery, PTFE is therefore better understood as a special-purpose engineering material that complements stainless steel and aluminum rather than replacing them.
PTFE-coated vibration channel of tablet counting machine
In terms of verifying machine materials, certificates are an important part of traceability, but they are not the only way. Manufacturers can also perform spot tests or material identification tests in person. This part is to introduce several methods to test machine materials.
304 stainless steel can be verified through instrumental analysis.
XRF analysis
XRF (X-ray fluorescence) is a much more useful method for actual material identification. The basic principle is that X-rays excite atoms in the material. When the atoms return to their normal state, they emit characteristic X-rays. The instrument analyzes these signals to determine which elements are present and, within the instrument's capabilities and calibration, their concentrations.
It analyzes the alloy's elemental composition, particularly elements such as chromium and nickel, and compares the measured composition with the expected range for the target grade. This allows a manufacturer to identify whether a material is consistent with a 304-type stainless steel rather than relying on appearance or magnetism alone.
XRF is especially practical for incoming-material inspection because it is fast and can be performed with portable equipment. ASTM (American Society for Testing Material) material-identification work likewise recognizes handheld XRF as a practical tool for rapid alloy verification, while noting its limitations for certain lighter elements.
XRF analysis
OES analysis
When a more detailed analysis is required, manufacturers can use OES (Optical Emission Spectroscopy). The basic principle is different from XRF: the metal surface is excited, producing characteristic optical emission lines from the elements present.
Manufacturers can use OES spectrometer to perform the analysis. This can be useful when:
In practice, manufacturers do not necessarily need to use all methods for every 304 component. For routine verification, XRF is often the more practical instrumental test.
OES spectrometer
316/316L stainless steel requires particular attention because it is often selected for components where higher corrosion resistance is required. The key elemental difference between 304 and 316-series stainless steel is the presence of molybdenum (Mo) at a characteristic level in 316/316L. This makes molybdenum an important indicator when manufacturers want to distinguish 316-series stainless steel from 304.
Molybdenum Test Reagent
One practical method is a molybdenum test reagent, sometimes referred to as a 316 stainless-steel identification solution. It is based on a chemical reaction between the reagent and the machine material. Because 316/316L contains molybdenum, the reagent can produce a characteristic reaction or color change that provides a preliminary indication of whether the material contains molybdenum.
The basic process is: Prepare the surface → Apply the reagent → Observe the reaction → Compare the result → Preliminary identification
This method is attractive for manufacturers because it requires relatively little equipment. It can be useful during incoming-material inspection or for quickly checking a selected machine component.
However, the reagent test is primarily a screening method. It does not provide a complete elemental composition analysis and should not be regarded as sufficient by itself to prove the exact grade or distinguish 316 from 316L.
For critical components, a manufacturer can therefore use the reagent test as an initial check and then perform instrumental analysis if necessary.
Molybdenum Test Reagent
XRF Analysis
XRF provides a more comprehensive approach to 316/316L identification. Using an XRF spectrometer, manufacturers can analyze elements such as Chromium (Cr), Nickel (Ni), and Molybdenum (Mo). The presence and relative amount of molybdenum are particularly useful when distinguishing 316-series stainless steel from 304.
Another advantage is that XRF testing is generally fast and can often be performed without cutting or destroying the component. Portable XRF instruments can therefore be useful for spot-checking materials on the factory floor.
OES Analysis
For situations where a higher level of material verification is required, manufacturers can use OES. OES can provide a more detailed elemental composition and is particularly useful when elements that are difficult to determine accurately using some portable XRF systems need to be evaluated. This can become important when a manufacturer needs to distinguish 316 from 316L, because the carbon content is one of the key differences between these two grades.
Aluminum alloy presents a different testing challenge because it is not one specific machine material. Different alloys can contain various combination of elements, such as magnesium, copper, zinc, etc.
XRF analysis
XRF can be used to analyze the elemental composition of an aluminum alloy. Depending on the alloy, the manufacturer may examine elements components by comparing the results with the expected composition of the specified alloy.
However, portable XRF systems can have limitations with lighter elements, so the instrument's capabilities and calibration need to be considered when testing aluminum alloys.
Hardness testing
Chemical composition is not the only property that can be checked. A hardness tester can provide additional information about the physical condition of the material.
The basic process is: Apply a controlled force → Create an indentation → Measure the indentation response → Obtain hardness value
Hardness testing does not identify the alloy grade by itself. Instead, it provides a physical-property check that can supplement elemental analysis.
For critical components, manufacturers may therefore combine composition testing with appropriate mechanical-property testing rather than relying on one test alone.
A practical identification method to verify PTFE is FTIR, or Fourier Transform Infrared Spectroscopy. Manufacturer can use FTIR spectrometer to perform the analysis.
The basic principle is that chemical bonds within a material absorb infrared radiation at characteristic frequencies. These can form a characteristic spectrum and then be analyzed with reference spectra. The testing process can be summarized as: PTFE sample → Infrared scanning → Characteristic spectrum → Database comparison → Material identification
FTIR is also widely applicable to other polymers including PE, PP, PVC, etc. Therefore, when a pharmaceutical packaging machine specifies PTFE for an anti-stick component, FTIR provides a practical way to verify the polymer identity rather than relying only on visual inspection or the supplier's documentation.
FTIR spectrometer
For a buyer evaluating a pharmaceutical packaging machine, machine material verification should go beyond asking, "Can you provide a material certificate?" The more useful approach is to understand what material is used, where it is used, why it was selected, and how the manufacturer verifies it.
Certificates are an important starting point for verifying the specified grade of machine material. However, buyers should not rely on documentation alone when evaluating critical components of a pharmaceutical packaging machine.
During fabrication, materials may be cut, welded, machined, polished, or assembled, and the buyer ultimately needs to know whether the material actually installed in the machine corresponds to the material specified in the technical documentation.
Therefore, buyers can ask suppliers to provide a material identification and verification process, particularly for product-contact components.
For example, instead of simply asking whether a machine uses stainless steel, buyers can ask the supplier to specify the material used for each critical component. A product-contact hopper may use 316L stainless steel, while the machine frame may use 304 stainless steel. This component-level information provides a much clearer understanding of the machine's material configuration.
Buyers should also ask why a particular material was selected. For example, 316L may be selected for a product-contact part because higher corrosion resistance is required, while PTFE may be selected for a guide because its low friction and non-stick properties are beneficial for product handling.
For critical materials, buyers can also request test records or sample inspection results, where appropriate. This provides additional evidence that material verification is part of the manufacturer's actual quality-control process rather than simply a statement in the machine specification.
In addition to requesting material certificates and material verification records from the supplier, buyers can also conduct on-site machine material checks during the factory inspection.
Before the factory inspection, buyers should identify which components require material verification. Priority should generally be given to product-contact parts and other critical components, rather than attempting to test every individual part of the machine.
For example, if the technical specification states that the product-contact parts of a capsule filling machine are made of 316L stainless steel, the buyer can select representative components such as the powder hopper or dosing components for spot testing through Molybdenum Test Reagent.
Buyers can record the results with the following items:
This creates a direct connection between the technical specification, machine component, and test result.
Rich Packing’s Clients is Testing 316 Stainless Steal with Reagent
Machine material selection is a critical consideration in pharmaceutical packaging. The right material can help meet applicable regulatory requirements while providing mechanical performance and product protection required for different machine components.
Different materials also require different verification methods. For buyers, therefore, material verification should not stop at simply checking whether a supplier can provide material certificates. A reliable supplier should have a clear material-control process and be able to provide material certificates, inspection records, test results, and other relevant verification documentation for critical components. Where necessary, the supplier should also support on-site material testing or inspection during factory visits and machine acceptance.
Ultimately, an excellent pharmaceutical packaging machine supplier should not only tell customers what materials are used, but also provide traceable evidence of material selection, testing, and verification. This can provide a stronger foundation for equipment quality and regulatory confidence.
Rich Packing treats customer inspection with profession
316/316L offers higher corrosion resistance than 304 and is therefore often considered for demanding product-contact applications.
A molybdenum test reagent can provide preliminary screening, while XRF or OES can provide more detailed material verification.
XRF can analyze elements such as chromium and nickel for material identification, while OES can provide more detailed chemical composition analysis.
FTIR (Fourier Transform Infrared Spectroscopy) can identify PTFE by analyzing its characteristic molecular spectrum.
Yes. Buyers can select critical or product-contact components for on-site spot testing and record the component, specified material grade, testing method, and test result.
29+ years in pharmaceutical machinery, covering capsule filling, tablet pressing, blister packaging, tablet and capsule counting, cartoning, GMP production, and overseas machine service.
E-mail : manager@richpacking.cn
Building D, No. 226, Beishan Qiaotou Street, Haizhu District, Guangzhou City, Guangdong Province, China
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