CustomPartNet
·
October 16, 2026
·
Updated October 16, 2026
A good first step is to filter the supplier list down to shops that meet your must-haves, such as experience with polypropylene, the press tonnage your part requires, or specific quality certifications. Location matters too, since it affects freight cost and lead time. For larger volumes or long-term programs, choosing the right molder can matter as much as the part design itself. Ask to see sample parts that resemble your project. A molded sample shows surface quality, parting line control, and overall workmanship in a way a spec sheet cannot. Browse our supplier network to compare qualified Ohio suppliers, review sample parts, and request quotes.
Injection molding is the most commonly used manufacturing process for plastic parts. It handles a wide range of part sizes and complexity, and it is a natural fit for appliance programs because it turns out large quantities of consistent parts at a low cost per piece.
Raw plastic, usually in the form of small pellets, is poured into a hopper and fed into the barrel of the injection unit. A reciprocating screw rotates and slides axially, moving the material forward while pressure, friction, and surrounding heaters melt it.
When enough molten plastic has built up at the front of the barrel, the screw drives forward and injects the material through the nozzle into the mold. Pressure is held so the material is packed into the cavity as it starts to cool and solidify.
Once the part has cooled, the clamping unit opens the mold and the ejection system pushes the part out. The mold closes again and the cycle repeats. Cycle times are short, typically between 2 seconds and 2 minutes depending on the part.
Plastic housings are among the most common injection molded products. They are thin-walled enclosures, often with many ribs and bosses on the interior, which describes a large share of household appliance parts.
Polypropylene (PP) is a popular choice for appliance parts because it combines practical properties with a low material cost:
Lightweight, tough, and stiff
Good heat resistance
High chemical resistance to detergents, cleaners, and many household fluids
Scratch resistance
Low cost, which helps at high volumes
Natural living hinge capability for lids, flaps, and clips
Available in many colors and with mineral or glass fillers for added stiffness
The mold is the custom tool that gives the part its shape. It is typically made of steel or aluminum and consists of two halves, the mold core and the mold cavity, which form the part cavity when closed. Molten plastic reaches the cavity through the sprue, runners, and gates, while cooling channels carry water through the mold to pull heat out of the plastic.
Tooling cost is influenced by:
Part size and the size of the mold base
Part complexity and feature count
Side-cores, lifters, or unscrewing devices
Number of cavities
Tolerance and surface finish requirements
Expected production quantity
PP shrinks more than materials like ABS, so the mold and part design need to account for it. Uniform wall thickness is the best defense against warping and sink marks, because most molding defects trace back to uneven cooling. Other rules of thumb for appliance parts:
Add ribs for stiffness rather than thickening walls, keeping rib thickness to 50 to 60% of the wall and rib height under three times the wall thickness
Keep boss walls to no more than 60% of the main wall thickness and support them with ribs or gussets
Apply a draft angle of 1° to 2° on walls parallel to the parting direction
Round inside corners to at least the wall thickness
PP injection molding is used across the appliance industry to produce parts such as:
Washing machine tubs, agitators, and detergent dispensers
Dishwasher racks, spray arms, and filter housings
Refrigerator door bins, shelves, and crisper drawers
Vacuum cleaner housings and dust bins
Air purifier and humidifier components
Control panel bezels and knobs
Handles, lids, and caps
Internal brackets, clips, and covers
Water reservoirs and tanks
Small kitchen appliance housings
Ohio suppliers support prototype and production programs for appliance OEMs, startups, and contract manufacturers across North America.
PP offers a strong mix of toughness, chemical resistance, heat resistance, and low cost. It stands up to detergents, hot water, and everyday wear, and it is easy to mold into housings, bins, and covers in large quantities.
Tooling generally runs from $5,000 to $100,000+ depending on part size, complexity, number of cavities, and expected volume. Piece price depends on material weight, cycle time, and the size of the machine required. Thinner walls reduce both material use and cooling time, which lowers cost per part.
Typical tolerances fall between ±0.005" and ±0.020", depending on geometry, material grade, and tooling quality. PP has higher shrinkage than some other plastics, so tight tolerances on large or thick parts can be harder to hold. Discuss critical dimensions with your supplier early.
In many cases, yes. PP resists a wide range of cleaners and detergents and tolerates hot water well. Parts near heating elements or in sustained high-temperature areas may need a filled or heat-stabilized grade, so share the operating conditions with your molder.
PP can be molded with smooth, matte, or textured surfaces, and color can be added during molding to avoid secondary painting. Because PP has a waxy surface that resists paint and adhesives, parts that need printing or bonding usually require surface treatment.
Yes. Flame-retardant grades are available for parts near electrical components, and food-contact grades exist for items such as water reservoirs and food-handling parts. Confirm the required certifications with your supplier before material selection.
Yes. Many Ohio suppliers offer design for manufacturing feedback, prototyping, tooling, pilot runs, full-scale production, assembly, and packaging. Injection molding is most economical at medium to high volumes, since tooling cost is spread over more parts, and runs commonly range from thousands to millions.
Get competitive quotes from Ohio injection molding suppliers experienced with polypropylene appliance parts. Upload a CAD file, drawing, or product concept and receive quotes from qualified suppliers matched to your project.
Get Quotes Now → or Register for a Free Account → to discover new suppliers, create shortlists, and manage RFQs.