In aerospace engineering, weight and performance matter a lot. Even small weight savings can make a real difference. That is why picking the right core material is a big decision. So why has ROHACELL IG-F become a popular choice for many aerospace uses? It comes down to a strong mix of low density, high strength, and steady performance at higher temperatures. This polymethacrylimide (PMI) foam is a rigid, closed-cell material that contains no CFCs. It offers properties that match the strict needs of flight parts, from strength and stiffness to reliable manufacturing results.
Some ROHACELL® grades are made specifically for aircraft and space (such as ROHACELL® A or HERO). ROHACELL® IG-F started as an “Industrial grade,” but it is used in aerospace where its balanced set of properties works well. It handles tough processing conditions and gives stable mechanical performance. In many cases, this “standard” option still delivers very high results.
What Makes ROHACELL IG-F Ideal for Aerospace Applications?
Why Do Aerospace Engineers Prioritize Core Materials?
Aerospace engineers constantly work to reduce weight while keeping parts strong and stiff. Core materials are key in sandwich composite structures because they separate two thin outer skins (often carbon or glass fiber). This spacing creates a structure that is very stiff without adding much mass. Without a good core, thin skins can buckle under load, which makes the part unusable.
Choosing a core material involves trade-offs between strength, heat resistance, how well it works in manufacturing, and cost. Aerospace also demands predictable behavior in harsh conditions and strong safety margins. PMI foams are often used here because they can meet strict specs and keep performing over many years of service.
Key Properties of ROHACELL IG-F That Benefit Aircraft Design
ROHACELL IG-F stands out because of its PMI foam structure. PMI can form rigid, closed-cell foams that keep good mechanical properties at low density. The closed-cell design helps block moisture absorption, which can be a serious issue for other core materials (especially at high altitude where freezing can occur). Another benefit is resin control: resin mainly enters only the cut cells on the surface, which helps keep final part weight and resin use down.
With typical densities from 31 to 110 kg/m³, ROHACELL IG-F gives strong performance for its weight. It is rigid and stable at higher temperatures, handling cure temperatures up to 130°C. This matters because many aerospace resin systems (like epoxies) need higher temperatures to cure properly. Its “coarse/medium” cell size, plus the “F” style that limits resin uptake, helps create good bonding without soaking up too much resin. This balance supports many composite manufacturing methods.
How Does ROHACELL IG-F Compare to Other Aerospace Core Materials?
ROHACELL IG-F vs. Honeycomb Structures
Honeycomb cores have been used in aerospace for a long time because they offer a strong strength-to-weight ratio. But they also bring problems that ROHACELL IG-F helps avoid. Honeycomb often needs a more expensive two-step cure cycle, which adds time and process steps. Honeycomb can also be damaged by freezing: if the outer skin cracks, water can enter the cells and then expand as it freezes, causing major damage. Removing water and debris from honeycomb can also be difficult.
ROHACELL IG-F has a 100% closed-cell structure, so it does not soak up water. If the skin is damaged, water does not spread through the core, which keeps the damage area smaller and easier to manage. This moisture resistance improves durability and can make inspection and repair simpler.
ROHACELL foam cores are also homogeneous and isotropic, meaning their properties are similar in all directions. This helps avoid extra cure steps or extra materials that honeycomb may need at edges and cutouts.
Comparison with Other Foam Cores
Compared with traditional polyurethane (PU) foams, ROHACELL IG-F is a better fit for demanding aerospace parts. PU foams can have uneven cell structures, leading to weak areas and “soft spots” from production variations. ROHACELL is a rigid, closed-cell foam with a more uniform structure, so it typically provides higher shear strength and compressive stiffness at the same density. This can let engineers choose a lower density core for the same strength target, which saves weight.
Heat resistance is another major difference. Many PU foams soften or release gases at about 80°C to 100°C, which limits them in autoclaves or heated mold cures. ROHACELL IG-F stays stable up to 130°C and holds its shape under vacuum pressure at higher temperatures, which supports vacuum bagging and autoclave processing. This makes it compatible with higher-performance resins like epoxies or BMI systems. It also helps keep resin use lower, since ROHACELL does not act like a sponge the way many PU foams can.
Performance Advantages of ROHACELL IG-F in Aerospace
Lightweight Construction and Density Efficiency
Aerospace design is strongly driven by weight reduction. ROHACELL IG-F supports lightweight structures while keeping good strength. It is available in low densities such as 31, 51, 71, and 110 kg/m³, helping designers reduce mass without giving up structural needs. For aircraft, lower weight can mean less fuel burn, more payload, longer range, and better handling.
Because it improves strength-to-weight performance, ROHACELL IG-F helps engineers design more efficient shapes and structures. Weight savings also bring business and environmental benefits, since every kilogram saved can reduce operating costs and emissions over time.
Exceptional Heat Resistance and Thermal Stability
Aircraft parts see wide temperature swings, from very cold conditions at altitude to heat during manufacturing and operation (for example near engines or in areas with strong airflow heating). ROHACELL IG-F can handle curing temperatures up to 130°C, which fits many epoxy systems that need higher-temperature curing. Unlike foam cores that can soften, gas out, or collapse, ROHACELL IG-F keeps its shape during cure.
This stability supports strong bonding between the core and composite skins and reduces the risk of delamination or voids. During service, stable performance through temperature changes improves safety and part life. For higher temperature needs, other ROHACELL grades like HERO or XT can reach about 180°C to 190°C, but IG-F is a strong choice for many standard processes, especially when sourced through a specialist supplier such as Chem-Craft.
Outstanding Creep Compression Strength
Many aircraft structures experience constant loads and vibration for long periods. Creep compression strength describes how well a material resists long-term deformation under compressive stress, especially when warm. ROHACELL IG-F has very strong creep resistance compared with other rigid foams. This helps parts keep their shape and performance over many flight hours and load cycles.
In parts like helicopter rotor blades, which face high fatigue loads and must keep precise aerodynamic form, resistance to creep helps prevent slow shape change over time. Holding geometry helps maintain efficiency and supports long-term safety.
Process Compatibility and Versatility
Usability with All Composite Manufacturing Processes
Aerospace composites are made using many different processes. ROHACELL IG-F works well with most of them, including hand layup, Resin Transfer Molding (RTM), vacuum infusion, and autoclave processing. Because it is rigid and stable at heat, it can handle the pressures and temperatures used in these methods.
It can serve as a load-bearing core in sandwich structures, and it can also be used as a tool material in processes like fiber placement, filament winding, and flyaway mandrels. This flexibility can simplify production and reduce the need to switch materials between projects.
Thermoforming and Machining Benefits
Modern aircraft often need complex shapes for better aerodynamics and packaging. ROHACELL IG-F can be thermoformed into detailed shapes, giving designers more freedom than many traditional materials. At about 175°C to 220°C (depending on grade and density), ROHACELL becomes thermoelastic and can be formed into precise 3D shapes. (Even though IG-F has a maximum curing temperature of 130°C, it can be formed at higher temperatures for short periods.)
It is also easy to machine using common methods like milling, drilling, turning, and sanding, often without lubricants. This supports accurate shaping on CNC machines used for wood and plastics. Evonik’s SHAPES department can also supply fully machined ROHACELL cores made on 4- and 5-axis CNC mills, showing how well the material fits automated, high-precision production.
Adhesion and Resin Management for Sandwich Structures
In sandwich composites, the bond between the core and skins is extremely important. ROHACELL IG-F supports strong adhesion while keeping resin use under control. Because it is closed-cell, resin mainly enters surface cut cells rather than soaking deep into the foam. Resin uptake for fine-celled ROHACELL grades can be around 50 g/m², far less than many open-cell foams. The “F” in IG-F points to a fine cell structure aimed at reducing resin absorption.
Lower resin uptake reduces added weight and lowers resin costs, which matters a lot in aerospace programs using expensive resins. ROHACELL IG-F can be bonded with most commercial adhesives, and after proper dedusting, the cut-cell surface provides good mechanical grip for reliable bonding. This helps produce strong bond lines without extra mass.
Aerospace Certifications, Safety, and Standards
Meeting Aircraft Industry Approvals
To be widely used in aerospace, a material must meet strict approvals and specifications. ROHACELL has a long record here. The first aerospace ROHACELL specification was written soon after production started in 1972. Today, many customer specifications define property targets for ROHACELL grades across many aircraft and aerospace platforms. ROHACELL WF was developed to meet MIL and CMS specifications for tough aerospace needs. ROHACELL IG-F is often used in aerospace-related industrial applications where its overall balance is a good match, and it can also serve as a starting point for more specialized needs.
This long history, plus ongoing product development, has helped ROHACELL become a trusted material for decades. Long-term testing and certification work also support its use in safety-focused applications.
Integrated Quality Management for Aerospace
In aerospace, consistent manufacturing quality is as important as the material itself. Evonik, the maker of ROHACELL, uses an integrated management system certified to major aerospace standards, including EN 9100:2018/ AS9100:2016 and ISO 9001:2015. These certifications cover development, production, configuration management, and quality control, helping keep product quality consistent for aerospace requirements.
Evonik has also been listed in the OASIS (Online Aerospace Supplier Information System) database since March 2007. This supports its role as an approved supplier for many aerospace customers. For engineers, this kind of quality system helps build confidence that ROHACELL IG-F is produced in a controlled and repeatable way for flight parts.
Environmental Impact and Sustainability of ROHACELL IG-F
Recycling and End-of-Life Considerations
Sustainability matters more each year, even in high-performance aerospace programs. ROHACELL IG-F is a closed-cell PMI foam that is largely physiologically inert and non-hazardous. Based on current knowledge, it has no harmful effects on humans, animals, plants, or microorganisms under normal conditions. It does not dissolve in water and is not absorbed through skin, lungs, or digestion due to its high molecular weight. ROHACELL is not typically recycled into new material in the usual way, but disposal is straightforward and does not pollute water.
For end-of-life handling, incineration in a normal combustion plant is preferred over landfilling, following local rules. Even without classic recycling, its lightweight and durable performance supports sustainability by reducing fuel use and helping aircraft parts last longer.
Material Resource Efficiency in Aerospace Design
The biggest environmental benefit of ROHACELL IG-F often comes from system-level savings. Lighter aircraft parts reduce fuel consumption and emissions over the aircraft’s service life. ROHACELL also offers good fatigue resistance and impact tolerance, which can extend part life and reduce how often parts need to be replaced.
Low resin uptake also reduces the amount of resin needed during manufacturing, which improves resource use at the production stage. By supporting lighter structures that perform well over time, ROHACELL IG-F helps aircraft makers reduce total resource use and operating impact.
Factors to Consider When Selecting ROHACELL IG-F for Aerospace Projects
Grades and Customization Options
ROHACELL IG-F is a flexible choice, but ROHACELL also includes many other grades for different targets. ROHACELL A is a base grade qualified for aircraft use. ROHACELL HERO offers much higher elongation at break, which improves damage tolerance and suits many commercial aircraft Class A and B parts. WF grades are used for radomes and antennas, and XT offers the highest temperature and compressive resistance.
ROHACELL IG-F is available in several densities (31, 51, 71, and 110 kg/m³), so engineers can match weight and strength needs to the part. Working with experienced distributors such as CHEM-CRAFT, an official Evonik partner, can help with grade selection and technical support. Their composite engineering team can help pick the right grade and reduce development time and specification mistakes.
Total Cost of Ownership Analysis
ROHACELL IG-F can cost more upfront than basic foams like polyurethane. But looking at the full cost over the project often changes the picture. One key factor is low resin uptake, which can save money on expensive epoxy or BMI resins. Less resin also means less extra weight, which improves aircraft performance.
ROHACELL IG-F is also easier to machine and handle than many alternatives, which can reduce labor time and tool wear. Its stable behavior during cure can lead to fewer rejected parts and less scrap. Over time, better durability, fatigue resistance, and impact performance can also lower maintenance costs and extend service life. When these factors are added up, ROHACELL IG-F often becomes a cost-effective option for high-end composite manufacturing.
Examples of Aerospace Applications Using ROHACELL IG-F
Typical Components Benefiting from ROHACELL IG-F
Because of its balance of low weight, strength, and thermal stability, ROHACELL IG-F fits many aerospace components. It is often used in primary structures like pressure bulkhead stringers and floor panels, where weight and strength both matter. Control surfaces also benefit, since weight reduction can improve handling response. Radomes, which need structural performance and electromagnetic transparency, often use ROHACELL (including HF grades), and IG-F can work as a general-purpose option in some designs.
ROHACELL is also used in helicopter rotor blades, where creep resistance helps keep the blade shape stable under heavy fatigue loading. Other parts include landing gear doors, belly fairings, flaps, spoilers, elevators, rudders, and nacelles. These structures often face impact risks, and ROHACELL’s closed-cell design and visible damage behavior can be helpful for inspection and repair.
Performance Case Studies and Success Stories
Real use cases show how ROHACELL performs in aerospace. A partial composite helicopter main rotor blade made by Van Horn Aviation (USA) for the 206B JetRanger helicopter used a ROHACELL 71HERO foam core with Toray carbon fiber. This example shows how ROHACELL can support demanding structural parts and maintain blade shape over time.
A study by the Fraunhofer Institute also reported strong performance for ROHACELL HERO, showing it can survive common impact scenarios and makes impact damage easier to see after a hit. While IG-F does not match HERO’s very high elongation, IG-F still brings the core advantages of the ROHACELL family: steady structural performance, reduced water entry after damage, and easier repair compared with moisture-sensitive core options.
What Sets ROHACELL IG-F Apart for the Future of Aerospace?
New Developments and Ongoing Innovations
Aerospace keeps pushing for lighter and stronger structures with efficient production. ROHACELL, including IG-F as a core product, continues to improve through research and development from Evonik. New grades are introduced to meet specific needs, such as finer cell structures to reduce resin uptake even more, higher heat resistance for tougher cure cycles, and updated formulations for faster, higher-volume production. ROHACELL HERO, for example, increased elongation at break compared to other grades, improving damage tolerance for commercial aircraft parts.
This steady work keeps the ROHACELL family ready for future aircraft requirements. Improvements in PMI foam technology and manufacturing knowledge also help raise quality and expand how different grades can be used, including IG-F.
Industry Trends in Lightweight Materials
Lightweight materials are now a long-term direction in aerospace, driven by fuel cost pressure, stricter environmental rules, and the need for better range and payload. This requires materials with strong stiffness and strength at low weight. ROHACELL IG-F matches this need in a way many competing materials cannot.
More aerospace programs are also using automated composite production, which increases the value of materials that machine well, perform consistently, and work across different processes. As part designs become more complex and production scales up, the process fit, machinability, and stable quality of ROHACELL IG-F will matter even more. It supports what aerospace needs today and helps make future designs possible where older materials fall short.
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