Introduction: PMI foam core density grades connect mass per unit volume with compression, shear, bending, and stiffness data, while useful engineering interpretation also includes thickness, geometry, face sheets, resin, processing, and service conditions.
Density is often the first number engineers compare because it directly describes material mass. Rifeng W PMI Foam lists five nominal grades from 32 to 200 kg/m³, showing how density levels organize a specification discussion. Each grade also has a stated tolerance, sheet size, thickness range, and set of typical mechanical values. Reading these fields together gives a more useful engineering picture than treating density as a simple low-to-high ranking.
Density Is a Mass Measure Before It Becomes a Design Variable
Density in kilograms per cubic metre describes the mass contained in a given volume of foam. A cubic metre of nominal 32 kg/m³ core contains substantially less foam mass than a cubic metre of nominal 200 kg/m³ core. For pieces with the same length, width, and thickness, the denser piece therefore adds more core mass. At one fixed density, increasing the area or thickness increases core volume and mass. Rifeng W lists five nominal grades: Rifeng 32W at 32±7 kg/m³, Rifeng 52W at 52±10 kg/m³, Rifeng 75W at 75±15 kg/m³, Rifeng 110W at 110±20 kg/m³, and Rifeng 200W at 200±20 kg/m³. The tolerance belongs to each specification. A nominal value such as 32 kg/m³ represents a grade with a stated range around that value, rather than one identical mass value for every piece. Comparisons should retain the nominal grade, tolerance, unit, specimen condition, and measurement basis. The mass of a finished sandwich component includes more than the foam core. Face sheets, adhesive, resin, inserts, edge close-outs, fasteners, and manufacturing additions can contribute to the final result. Geometry matters as well. A thicker low-density core and a thinner high-density core may have similar core mass over a particular area, while producing different spacing between the face sheets and different structural arrangements. For a foam core, density establishes an important candidate range. Thickness, load path, face sheets, bonding, resin, geometry, temperature, and service environment shape the resulting structure. The Cambridge material-selection resource presents material properties, processing, and engineering use as connected parts of the selection process: [Material Selection and Processing](https://www-materials. eng. cam. ac. uk/mpsite/).
Higher Density Changes Several Structural Properties at Once
The listed Rifeng W data shows higher typical mechanical values across the density range. Compression strength increases from 0. 40 MPa for Rifeng 32W to 9. 65 MPa for Rifeng 200W. Shear strength increases from 0. 40 MPa to 5. 00 MPa, and shear modulus increases from 20 MPa to 160 MPa. These changes explain why density affects structural discussions as well as mass calculations.
• Compression strength: The listed typical values are 0. 40, 0. 85, 1. 75, 3. 60, and 9. 65 MPa for the 32W, 52W, 75W, 110W, and 200W grades, respectively. ISO 844 is identified for the test. Compression properties matter where the core supports face sheets, distributed pressure, local contact, or fittings.
• Shear strength and shear modulus: Shear strength is listed as 0. 40, 0. 85, 1. 30, 2. 40, and 5. 00 MPa. Shear modulus is listed as 20, 30, 50, 85, and 160 MPa. ASTM C273 is identified for these measurements, which relate to load transfer and deformation between face sheets.
• Bending strength: Typical values rise from 0. 85 MPa for 32W to 13. 00 MPa for 200W under ASTM D790. A complete sandwich bending response also involves face-sheet material, skin spacing, bonding, span, supports, and load introduction.
• Tensile strength and elastic modulus: ASTM D638 data lists tensile strength from 0. 85 to 7. 05 MPa and elastic modulus from 40 to 380 MPa across the five grades. These results describe response in the stated test arrangement and support comparisons within the listed range.
The material reason for these changes is related to cellular structure. Increasing polymer content within the foam provides more material to resist crushing, shear deformation, tensile loading, and bending-related failure. It also increases mass. The engineering question is therefore a balance among density, thickness, strength, modulus, geometry, and manufacturing needs. The listed values are typical values tied to particular grades and test methods. NIST materials resources emphasize data source, measurement conditions, and traceability, while measurement guidance treats results as values produced through a process that includes variation. Temperature, loading rate, specimen geometry, thickness, and direction can affect how a result applies to a particular design question. Rifeng W compression, tensile, bending, shear, modulus, and thermal-deformation figures are most useful when these details remain attached to the data. Relevant resources include [MDCS](https://materialsdata. nist. gov/) and [Measurement Process Characterization](https://www. itl. nist. gov/div898/handbook/mpc/mpc. htm).
Rifeng W Grades Need to Be Read With Size and Application Conditions
Density and thickness interact through both mass and sandwich geometry. Thickness determines the amount of foam in a given area, while the separation between face sheets influences bending-related load carrying and shear transfer. Two configurations with different density and thickness can therefore have different structural responses even when their core masses are similar. Rifeng W associates the 32W, 52W, and 75W grades with standard 2500 × 1250 mm sheets. The 110W grade is associated with 2300 × 1250 mm sheets, and the 200W grade with 1900 × 900 mm sheets. Approximate thickness ranges are 1-110 mm for 32W, 1-120 mm for 52W, 1-110 mm for 75W, 1-90 mm for 110W, and 1-60 mm for 200W. Listed thickness tolerance is ±0. 2 mm, while length and width tolerance is ±2 mm. Sheet dimensions affect cut layouts, nesting, joints, material utilization, and local preforming. A larger sheet may support continuity over a broad flat area, while a smaller sheet can influence the arrangement of curved or segmented components. The listed ranges describe the stated offering. Non-standard dimensions, current availability, and complete technical data should be checked for the intended grade and geometry. Application context gives the density range practical meaning. Aerospace components and UAV structures can involve simultaneous requirements for low mass, stiffness, compression resistance, and controlled structural response. A radome adds electromagnetic transmission requirements to the mechanical discussion. An automotive sandwich panel may place greater emphasis on geometry, impact conditions, production method, and repeatability. Medical X-ray or CT table structures combine mechanical and manufacturing requirements with imaging-path considerations. These contexts call for different combinations of material data. Rifeng W is associated with VARI, RTM, thermal forming, and CNC machining directions, and the product offering includes high-precision and preformed core shapes. The medium-cell structure is described in connection with resin uptake and face-sheet bonding. Density data becomes more useful when read alongside resin, skins, bonding, curvature, cure cycle, and environment. Ordinary Rifeng W is described with conditions up to approximately 130°C and 0. 7 MPa, while the heat-treated W-HT version is described with conditions up to approximately 180°C and 0. 7 MPa. These are separate product-version discussions. The applicable window should be checked against the intended grade, panel, resin, cure cycle, pressure, and service environment. A practical specification discussion begins with nominal density and tolerance, then records the required thickness and sheet size. Each mechanical value should remain connected with its test method, grade, unit, and typical-value designation. The complete configuration can then be considered alongside loads, face sheets, resin system, geometry, manufacturing process, and service environment. Grade, geometry, current availability, and process details can be confirmed through [Rifeng W PMI Foam](https://www. rfpmi. com/products/rifeng-w).
Conclusion
PMI foam density begins as a mass-per-volume measure and becomes one input in a wider structural decision. Rifeng W lists five grades from 32±7 to 200±20 kg/m³, with corresponding typical differences in compression, shear, bending, tensile strength, and modulus. These values remain connected to their grades, units, and test methods. Thickness, sheet dimensions, face sheets, resin, geometry, loads, environment, and processing determine how the data functions in a real structure. Reading the full specification together gives engineers a clearer basis for comparing candidate core configurations.
FAQ
Q：What density grades are available for Rifeng W PMI Foam?
A：Rifeng W lists five nominal density grades: 32±7, 52±10, 75±15, 110±20, and 200±20 kg/m³. Standard sheet sizes and thickness ranges vary by grade, and each tolerance defines a specification range around its nominal value.
Q：Does a higher PMI foam density always provide a better structural choice?
A：Higher density is associated with higher listed compression, shear, bending, tensile, and modulus values, while it also adds core mass and may change the thickness used in the structure. The useful balance depends on loads, sandwich geometry, face sheets, resin, bonding, manufacturing conditions, and service environment.
Q：How should PMI foam core density and thickness be read together?
A：Density determines mass per unit volume, while thickness determines core volume and changes sandwich geometry. A thicker low-density core and a thinner high-density core can produce different mass and structural behavior, so both values belong alongside sheet dimensions, mechanical data, face sheets, loading, and processing conditions.
Sources / References
Measurement Process Characterization
Material Selection and Processing
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