Starting materials

The selection of the components of a fiber composite material, i.e. the reinforcing fibers and the matrix embedding them, in conjunction with the manufacturing process, determine the properties of the composite. In contrast to many other materials that are already purchased by the product manufacturer as semi-finished products or pre-produced according to standards, the optimum characteristic values of a fiber composite plastic can only be achieved through the interaction of the right technology and trained, knowledgeable employees in the design and production areas.

Hahlbrock processes almost all types of fiber materials based on glass, carbon and aramid (Kevlar ^® ). Tailored to the function, technical environment and economic aspects of the molded part, these fibers are specified in their confection and processed with unsaturated polyester, epoxy or vinylester resins to produce a specifically lightweight and high-strength molded part. The pre-hardened molded parts are generally thermally post-treated (tempered) according to the resin manufacturer’s specifications.

In addition to the classic properties of fiber composite materials, such as specifically low weight with high strength, good corrosion resistance and excellent formability, other advantageous material properties can be generated. We benefit from a long, trusting collaboration with our resin suppliers, which enables us to rely on a large number of special formulations of standard resins and to test them in-house for their suitability on a project-specific basis. For example, resins have been made process-safe for sophisticated manufacturing processes and new areas of application, for example in construction, have been opened up through high translucency, elasticity or fire resistance.

Manufacturing methods

Hahlbrock uses a variety of methods to produce molded parts. Trained and knowledgeable employees in the production area always ensure high quality, whether in the material selection, execution or on-time completion.

INJECTION PROCESS / RTM-light

The different injection processes enable high fiber content and correspondingly high strength. Further advantages of the closed-loop process are low-emission processing and low spread of quality-relevant parameters. The fiber products are inserted dry into the mold. Under the influence of a pressure gradient, resin is injected into the prepared reinforcing material.

Prepreg process (autoclaveless)

In FRP production with prepregs that can be processed without an autoclave, fiber reinforcements impregnated with pre-crosslinked synthetic resin (fabric, scrim or UD made of glass or carbon fibers) are placed into the mold, only compressed only under atmospheric vacuum (max. 1 bar) and then subjected to controlled thermal curing.
In one variant, the reinforcing fibers in the form of roving strands, fabrics or laid fabrics are still dry and coated with separate, also pre-crosslinked pure resin films, which only become liquid when heated and penetrate the fiber reinforcements.

HAND LAMINATE

This process is particularly suitable for prototypes and small series, but also for large-format and geometrically complex molded parts. After a top layer has been applied and hardened, the fibers are placed in the open mold for lamination in the form of mats or fabrics and soaked in resin. After each layer, trapped air is removed by rolling it out. The next layer is then applied. After curing at room temperature, the parts are demoulded and reworked.

FIBER SPRAY PROCESS

The fiber spraying process is a partially mechanical version of hand lamination. The activated resin is sprayed onto the mold together with cut glass fiber rovings and then vented by rolling it out.

WET PRESSING

The most frequently used process in the production of FRP molded parts in medium and large series. Mat cuts are placed in the tool and covered with the activated resin. Under the pressure of the closing mold upper part, the resin is distributed in the mold (cavity) and saturates the fibers.