Western Industries Plastic Products, LLC > Blow Molding vs Other Processes

Blow Molding vs Other Processes

What is Blow Molding?

One of the most popular plastic manufacturing processes to create hollow plastic parts of various shapes and sizes by inflating a viscous plastic tube, or parison until it fills a mold and forms the desired shape. Think of it as inflating a balloon inside a water bottle. Once the plastic has cooled and hardened, the mold is opened and the finished product is ejected.

Is Blow Molding the Right Choice?

The fastest most cost-effective plastic molding process is blow molding when your production volume reaches 3,000+ parts per year. Also, when your increasing focus is on lightweight and sustainability. For this reason and many others, blow molding is an emerging process for larger-scale production needs.

The Benefits of Blow Molding

This plastic process can offer great benefits vs other processes. Those include a faster production rate and tighter tolerances. More conducive to the production of mid to higher volumes. Vastly improved design capabilities. Part shape, complexity, and size are rarely an issue. Lower tooling costs than other processes.

Blow Molding vs Other Processes

Rotational Molding

Rotational Molding, also known as Roto Molding, is a plastic molding technology for making hollow parts. It is a casting technique that is used, unlike most other processes where there is no pressure involved.

If you’re producing fewer than 2,500 pieces of product annually, you might be better off using roto-molding due to tooling costs. But if your production volumes are higher annually, Blow Molding should always be considered due to lower piece prices and overall project costs.

Drivers are Design, Production Rate, and Piece Price.

DESIGN

Blow Molding allows for greater design flexibility than rotational molding. Blow molding can produce a wider range of shapes and sizes, including complex geometries and thin-walled parts. Blow molding can also produce parts with high precision, which is useful in applications where dimensional accuracy is important.

PRODUCTION RATE

Blow Molding is typically faster than rotational molding, which can result in lower production costs. Blow molding can produce parts in a matter of seconds, while rotational molding can take several minutes or even hours, depending on the size and complexity of the part.

PIECE PRICE

Blow Molding is typically more cost-effective than rotational molding for large production runs, as the initial tooling costs can be spread out over a larger number of products. Additionally, blow molding is faster than rotational molding which can lead to increased productivity and lower overall costs.

Injection Molding

Plastic Injection Molding or commonly referred to as injection molding, is a manufacturing process used in the fabrication of mostly solid thin-walled plastic parts. Unlike blow molding, there is not as much design freedom allowed.

The most widespread use of injection molding is making non-consumer parts used in situations where visual appeal doesn’t matter – like mechanical parts – because the injection molding process often leaves impurities behind on the plastic parts.

Drivers are Tooling, Processes, and Design.

TOOLING

Blow Molding typically has lower tooling costs than injection molding. This is because blow molding used a single mold, while injection molding requires multiple molds for different parts of the product. In addition, blow molding molds are typically made from less expensive materials than injection molding molds.

PROCESSES

Blow Molding can produce parts with a smoother, more consistent surface finish than injection molding. This is because blow molding used a mold that is designed to produce the desired surface finish, while in injection molding, the surface finish can be affected by the movement of the mold during the cooling process.

DESIGN

Blow Molding creates hollow parts. The mold has more design freedom between mold halves since each mold half forms its own wall shape.<br>Injection Molding creates solid parts. Due to geometry constraints, injection molding is not well suited to thin-walled parts.

Thermoforming

Twin Sheet Thermoforming is a process in which two sheets of plastic are heated until pliable and then fitted around two custom molds at the same time. After the sheets are shaped using pressure they are fused together.

Thermoformed parts are most commonly used in the food packaging industry. However, the process is limited in geometry, required wall gauge, draw ratios, and undercuts. All of which are very difficult to achieve with thermoforming.

Drivers are Price, Processes, and
Design.

PRICE

Blow Molding has faster cycle times that allow for better economies of scale, and potentially fewer secondary requirements that produce a more cost-effective part. Thermoforming has longer cycle times and typically far greater secondary requirements that add additional costs.

PROCESSES

Blow Molding is consistent in using first-generation regrind eliminating added costs.
Thermoforming uses sheet templates that frequently add scrap usage and add to costs.

DESIGN

Blow Molding may offer the ability to produce a 2-up part that comes from a single mold, which is rarely an option in thermoforming. This represents another potential area of reduced costs due to increased production rates.

Learn How Blow Molding Works

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More than just plastic bottles, Blow Molded products can be produced for a variety of industries, and are a cost effective alternative to injection molding. Just fill in your information below and we’ll send you your free checklist