Plastic Assembly Methods

Our in-house resources enable rapid plastic assembly method development and reduce risk during transfer to manufacturing

We recommend to our clients the assembly methods that will meet all product requirements at the lowest risk and cost. As specialists in medical disposables, we have extensive experience with all plastic assembly methods including press fits, snap fits, swaging, interlocks, UV bonding, pressuresensitive adhesive, thermal bonding, ultrasonic welding, laser welding, etc. All plastic assembly methods are developed using production quality equipment onsite which allows us to complete iterations quickly and demonstrate a robust assembly process that is ready for high volume manufacturing. Our goal is to simulate the manufacturing environment here at Symbient which makes the transfer to manufacturing an exercise rather than a process that involves risk. We stay current in our industry and take on new methods of plastic assembly to aid in the manufacturing processes for our clients’ products. 

Advanced Plastic Assembly Methods and Equipment 

Heat sealing is the process of bonding one thermoplastic to another similar thermoplastic using heat and pressure. The direct contact method of heat sealing utilizes a constantly heated die or sealing bar to apply heat to a specific contact area or path to seal or weld the thermoplastics together.

Pros: It is a lower-cost option compared to laser and ultrasonic welding. Assembly can occur simultaneously on multiple planes and at multiple points.

Cons: There are material compatibility limitations to be considered.  The heat may also warp certain plastics depending on geometry. It may not be appropriate for heat-sensitive reagents.

Laser welding is vibration-free, particulate-free, and requires only very localized heat. This is a high-precision plastic assembly method that can be used for small or large parts and can be scaled up in manufacturing. It also allows for rapid prototyping with a reliable seal which is useful for projects that intend to use other methods in manufacturing such as ultrasonic welding but take longer to implement.  Ultrasonic welding requires the design and fabrication of a horn and nest which drives a longer lead time.  Prototypes may be temporarily fabricated using laser welding to enable testing to proceed while ultrasonic welding is developed in parallel. 

Pros: High precision, high accuracy, and high strength welds. Allows for sealing for applications that involve very high pressure or caustic reagents.

Cons: The top component must be clear and the bottom component must be opaque, preferably a dark color, or molded using a ‘clear weld’ additive to absorb the laser energy.

This plastic assembly method bonds two parts together by fusing them with ultrasonic energy applied to a precise area using an ultrasonic horn. Part design for ultrasonic welding, as well as horn and next design experience, is critical to successfully implementing this method.

Pros: Ultrasonic welding is a very robust and cost-effective assembly method. In addition, the equipment and tooling costs are low in comparison with other processes.

Cons: One of the limitations of this method is the vibration imposed on components by the process. Some materials, such as unreinforced semi crystalline materials, pose special challenges. Parts must be able to withstand the vibration, and the properties of these materials may be adversely affected by exposure to ultrasound.

Can you create low-volume assemblies of my product?

Yes, for all of our development projects, we can mold and assemble low volumes of your product for testing, development, user studies, etc. Our injection molding and assembly equipment is identical to the machines used in production. This allows us to supply you with devices that are identical to production assemblies, enabling you to perform more extensive testing earlier in development to reduce risk and accelerate your product release. Symbient has capacity to fabricate several thousand units and can assist with transfer to manufacturing as quantities increase.

What if I need clean room assembly?

We have a clean room available in our assembly area. The controlled environment of a clean room can help ensure that dust and other particulate matter does not contaminate your product. We can also accommodate specialty requirements such as RNAse free assembly. The clean room can be set up in different configurations depending on your clinical trial or other testing requirements.