“Helmet Safety Shell Manufacture Part2”

Motorcyclists & Motorsport enthusiasts, buckle up for a compelling journey that unveils the crucial link between helmet safety and your passion for adrenaline. We shed light on the specific risks you face, and the devastating consequences of Traumatic Brain Injuries (TBIs), & present an innovative solution to fortify your protection.

Welcome to The Helmet Doctors, where we strive to empower you with the knowledge and tools to ensure a safe and exhilarating ride/drive every time knowing your helmet’s structural integrity is in optimal condition.

Below and the following stories we will brief you on the areas:

• The Hidden Dangers,
• The Unseen Perils of TBIs & Death,
• How to Empower Prevention through Preventative Measures & Helmet Laser Scanning,
• The Simplicity of Taking Action to Enhance Your Safety,
• How you can become a Beacon of Hope for others,
• How Joining our Passion for Advancements in Helmet Safety Can Save Lives and How It Just Might Be Yours That Counts.

But now let’s look at …

Manufacturing Of Motorcycle Helmets – 

The Outer Shell: Composite Shells

Composite shells

There are two possible methods generally used for the manufacture of composite shells. 

The first utilises a positive mould and a negative mould. A releasing agent and a cover layer of resin, which contains the colour of the helmet and forms the outer thinnest layer of the helmet, are sprayed into the negative type mould. Thin strips of pre-cut glass fibre mats impregnated with highly viscous polyester resin and hardener are applied to the still-moist covering layer (Shuaeib et al. 2002b). A maximum of nine layers of polyester-type glass fibres are manually applied and pressed into the negative-type mould using special tools, to avoid the presence of bubbles (Hartung 1981). 

The second manufacturing method, begins with the application of a thin layer of resin, generally epoxy, to the positive type mould (in this case, the foam inner liner of the helmet). An aramid, glass, or carbon fibre mat or tissue is then applied to the still-moist layer of resin. Referring to Figure 2 of our website, this fibre tissue (with dimensions approximately 100 cm by 45 cm) can be extended over the final positive type mould until the mould is covered up to the upper edge of the cut-out (Hartung 1981).

The laterally overhanging ends of the tissue are then tensioned appropriately until the entire surface of the positive type mould (foam inner liner) is covered uniformly up to a longitudinal chin-protecting region of the helmet to be built up without forcing the folds (Shuaeib et al. 2002b). The ends of the tissue are laterally folded over the longitudinal portions, forming the chin-protecting regions, which means that this relatively weak region is covered by two layers of tissue (Hartung 1981). 

Following the first tissue application to the foam inner liner (positive type mould), it is carefully impregnated with artificial resin and then covered by the second tissue using the same technique. Hartung (1981) showed that a total of five tissues, applied over the foam inner liner, is sufficient to satisfy tough safety requirements. The advantages and disadvantages of manufacturing composite shells for motorcycle helmets are outlined as follows:

Advantages

1. • Lower investment costs in terms of machines and processes

Disadvantages

1. • Labour-intensive manufacturing processes, and hence increased costs
2. • Less dimensional accuracy than thermoplastic shells due to the manual application of glass fibre mats
3. • Require further finishing processes, i.e., chipping and grinding
4. • Inner Liner

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