Introduction
The snorkel mouthpiece (commonly referred to as the "bite piece") is a core component of diving equipment that comes into direct contact with the human oral cavity. Its design quality directly affects the safety and comfort of the diving experience. The upper half of a snorkel is typically a semi‑rigid plastic tube, while the lower mouthpiece is mostly made of silicone. A well‑designed mouthpiece must achieve a balance across multiple dimensions, including material biocompatibility, structural ergonomics, manufacturing process precision, and functional reliability. This article systematically elaborates on the design and manufacturing principles of diving snorkel mouthpieces from four aspects: material selection, structural design, manufacturing processes, and core principles.
1. Material Selection: Physical Property Basis of Food‑Grade Silicone
1.1 Material Advantages of Silicone
Currently, mainstream diving mouthpieces generally use food‑grade silicone as the base material. Silicone is the preferred choice due to several key physical properties. In terms of elasticity, silicone has an elongation at break of 300% to 800% and a rebound resilience exceeding 95%, meaning that the mouthpiece can quickly recover its original shape after repeated biting. In terms of temperature adaptability, silicone maintains stable performance across a range from ‑50°C to 200°C, allowing normal operation in both cold‑water ice diving and tropical seas. In terms of chemical stability, silicone does not leach harmful substances such as bisphenol A, has a plasticizer migration rate below 0.01 μg/cm², and exhibits strong resistance to seawater corrosion and ultraviolet aging.
1.2 Ergonomic Matching of Hardness
The Shore A hardness of silicone is a critical parameter in the design. The biting force exerted by the human upper and lower jaws typically ranges from 20 to 60 newtons. If the material is too hard, it can easily cause gum compression and temporomandibular joint fatigue; if too soft, it provides insufficient support and is prone to collapse and deformation. Professional diving mouthpieces generally have a hardness controlled in the range of Shore A 15–30, with some high‑end products reaching Shore A 35–40. This hardness range precisely achieves the best balance between deformation resilience and oral fit—providing adequate support to secure the snorkel during biting while dispersing bite pressure and avoiding localized stress concentration.
It is worth noting that some mouthpiece designs employ a multi‑hardness composite structure: the main body material has a hardness of approximately Shore A 20, while reinforcement components with Shore A 50–90 are embedded in critical areas prone to puncture or fracture, thereby combining soft comfort with structural strength.
2. Structural Design: Evolution from General‑Purpose to Customization
2.1 Anatomical Structure of the Classic Mouthpiece
A typical diving mouthpiece consists of two main parts: a front part and a rear part. The front part extends from the proximal (inner) end inside the oral cavity to the distal (outer) end outside, forming a horizontal channel for air passage. The rear part is U‑shaped and includes a middle anterior section and a pair of rearward‑extending leg portions, which run along the upper and lower tooth rows respectively, extending back to the molar area.
Each leg portion is provided with inner and outer vertical flanges and a horizontal occlusal portion situated between them. The occlusal portion has upper and lower surfaces for the diver’s teeth to bite and secure the mouthpiece. Near the air vent, the mouthpiece is integrally formed with wing structures, from which sealing plates extend outward on both sides. Bite blocks are molded on the inner walls of these sealing plates. This design ensures that the diver’s lips remain closed when biting the mouthpiece, preventing saliva from flowing back into the air vent.
2.2 Key Ergonomic Design Elements for Optimization
Geometry of the bite wings: Traditional mouthpieces feature bite wings of constant thickness and width, which cannot accommodate individual differences in bite patterns. Modern designs employ bite wings with gradually varying thickness (a thickness difference of approximately 1–4 mm), with wing widths of 6–12 mm, lengths of 14–40 mm, and thicknesses of 2–8 mm. This tapered design better matches the dental arch morphology of different users and disperses biting pressure.
Compensation for upper/lower jaw misalignment: Different divers exhibit bite discrepancies such as overbite or underbite. Advanced mouthpiece designs incorporate an offset structure between the upper and lower occlusal surfaces. Combined with the tapered bite wings and specific occlusal planes, this allows the mouthpiece to accommodate both overbite and underbite conditions simultaneously.
Anti‑slip and sealing structures: At the connection between the mouthpiece and the tube body, special anti‑slip locking mechanisms are provided to ensure a secure attachment even during vigorous movement. The sealing plate structure keeps the diver’s lips tightly closed when biting, forming an effective seal.
2.3 Design Breakthroughs in Customized Mouthpieces
Traditional mouthpieces adopt a “one‑size‑fits‑all” generic design, which struggles to match individual variations. Customized mouthpieces achieve a breakthrough through their heat‑formable rear part—the occlusal portion of the U‑shaped rear part can be thermoformed to the user’s dental morphology after heating, providing a tailored fit at all contact points between the mouthpiece and the teeth. This design extends the occlusal contact area from a limited number of front teeth to a broader region along the dental arch, significantly reducing localized pressure.
3. Manufacturing Processes: Precise Control from Mold to Finished Product
3.1 Liquid Silicone Rubber (LSR) Injection Molding
The mainstream production process for diving mouthpieces is liquid silicone rubber (LSR) injection molding. Its working principle is as follows: at a specified temperature, the fully melted silicone material is injected at high pressure into the mold cavity through screw agitation, and after cooling and curing, the molded mouthpiece is obtained.
LSR injection molding employs a two‑component system—the two liquid components are metered in precise ratios at room temperature via a dedicated delivery system, thoroughly mixed in a static mixer, and then injected into the heated mold cavity. Upon contact with the hot mold, the two components undergo a crosslinking reaction and cure to form the final product.
3.2 Mold Design and Process Control
The core of mouthpiece mold design lies in cavity precision and temperature control. The mold typically consists of an upper mold, a lower mold, and a replaceable core, which is secured by snap‑fit structures and positioning pins for easy disassembly and replacement. The mold is equipped with cooling structures such as cooling fans and pre‑formed through‑slots to accelerate the molding cycle and improve production efficiency.
During the injection process, low‑temperature coolant is introduced into the mold water channels to keep critical areas at a low temperature, preventing the silicone from curing prematurely due to temperature rise as it flows through. This ensures smoother molding and a higher yield rate.
3.3 Thermoforming Customization Process
For customizable mouthpieces, an additional thermoforming step is required after manufacturing. The user soaks the mouthpiece in warm water for about 15 seconds or heats it with a hair dryer using warm air to soften it into a pliable state. The softened mouthpiece is then placed in the mouth and gently bitten to conform to the curvature of the upper and lower dental arches while avoiding sensitive gum areas. After cooling, the mouthpiece is set into a “custom‑fitted” shape and can be repeatedly reshaped without distortion. This process utilizes the shape‑memory principle of thermoplastic materials.
4. Core Principles: Integration of Biomechanics and Materials Science
4.1 Principle of Bite Force Dispersion and Transmission
The core mechanical principle of mouthpiece design lies in the rational dispersion of bite forces. When a diver bites down on the mouthpiece, the bite force is transmitted through the bite wings to the main body of the mouthpiece. If the bite wings are improperly designed, stress will concentrate on localized areas of a few teeth, leading to gum compression and temporomandibular joint fatigue. By extending the bite wings rearward along the dental arch and employing a tapered thickness design, the bite force can be distributed over a broader tooth contact area. In some designs, the bite wings terminate laterally at the first molars, achieving a more even load distribution.
4.2 Principle of Elastic Deformation and Resilience
The mouthpiece undergoes elastic deformation during biting—the bite wings bend under the action of bite force. The high elasticity of silicone ensures that this deformation fully recovers once the bite force is removed. This elastic mechanism, on one hand, provides sufficient friction to securely hold the mouthpiece in the oral cavity, and on the other hand, prevents mouthpiece failure due to plastic deformation.
4.3 Materials Science Principle of Thermoforming Customization
The thermoforming principle of customizable mouthpieces is based on the glass transition behavior of thermoplastic materials. When heated to a specific temperature (typically below 120°F), the material enters a rubbery state where molecular chain segment mobility increases, making the material soft and pliable. Under external force (biting), the material undergoes macroscopic deformation to match the tooth profile. Upon cooling, chain segment motion is restricted, the deformation is “frozen,” and the material retains the customized shape. Owing to the crosslinked network structure of silicone, this deformation is reversible within a certain range, allowing repeated reshaping.
4.4 Principle of Oral Environment Adaptation
Mouthpiece design must also account for the unique physiological environment of the oral cavity. The lips should remain naturally closed during biting, and the sealing plate structure ensures lip sealing. The curved profile of the mouthpiece must conform to the dental arch shapes of different users. The occlusal surfaces are typically designed with a micro‑matte texture to reduce adhesion to the oral mucosa and avoid dryness and discomfort after prolonged use. Together, these design features constitute a systematic adaptation of the mouthpiece to the oral environment.
Conclusion
The design and manufacturing principles of diving snorkel mouthpieces represent an interdisciplinary subject that integrates materials science, ergonomics, manufacturing engineering, and biomechanics. From precise hardness control of food‑grade silicone to ergonomic optimization of anatomical structures; from the sophisticated process of LSR injection molding to the personalized adaptation of thermoforming customization—every step reflects a “human‑centered” design philosophy. With continuous advances in materials science and manufacturing technology, future diving mouthpieces will achieve even higher levels of comfort, safety, and personalization.
WAVE China is a diving snorkel manufacturer. If you are interested in diving snorkels, please contact us.
