on March 6, 2018 in Blow Molds & Mold Making
Blow molds have unique design freedoms that aren’t possible with injection or compression molds. Many of these benefits are made possible by aluminum. Here’s why aluminum tops steel when it comes to blow molds.
Fast
Aluminum molds can be created 10 times faster than steel, so mold delivery is faster and less expensive. What’s more, high-grade aluminum has 50-70% faster cycle times than P-20 steel.
This occurs because aluminum has 5 times higher thermal conductivity than steel, and 8 times higher thermal diffusivity than typical P-20. This rate of heat transfer eliminates the need for costly conformal mold cooling. This also provides greater capacity yields per cavity than other processes.
Durable
It’s not only faster to produce aluminum molds, but once they are up and running, they are built to last. Aluminum blow molds are operated under relatively low production pressures, so tool wear is minimal. Millions of parts can be created from a single mold. Aluminum is also easy to weld, insert, modify, and repair.
It’s interesting to note that an aluminum material like QC-10 starts with a Rockwell hardness of 22 but, during use, its hardness increases to 27. That’s right, with more use, aluminum actually becomesmoredurable. Aluminum surfaces hold up for years of ongoing production.
Lightweight
While some aluminum alloys are stronger thansteel, most are a bit weaker. However, what aluminum lacks in brute strength it makes up for in weight: aluminum is much lighter than steel. In fact, steel is about 2.5 times heavier than aluminum, making aluminum the winner in the safety arena during mold building, handling, and set-up.
Versatile
A handful of blow mold shops are capable of designing and building complex in-mold secondary, decorating, finishing, and assembly operations in aluminum tools. When done correctly, these systems can provide six sigma repeatability and reduce final product costs dramatically.
Because functional performance varies widely between shops, request references. Go with suppliers willing to discuss the long-term performance of their in-mold examples.
Summary comparison of high-grade aluminum vs. P-20 steel
| High-grade aluminum vs. P-20 steel | |
| Creation time | 10x faster |
| Cycle times | 50%-70% faster |
| Thermal conductivity | 5x higher |
| Heat transfer | 8x higher |
| Weight | 2.5x lighter |
You really can’t beat the design freedom, low cost, long life, easy changes, higher output, and faster delivery offered by aluminum blow molds.
If your blow mold tool shop is also part of a full-service blow molding production manufacturer, then you know your tool maker will make sure you have the quality that will last.
Looking for more? Check out our blog on howyour blow molder optimizes your product.
FAQs
What are the advantages of blow molding? ›
- Low tool and die cost.
- Fast production rates.
- Ability to mould complex parts.
- Handles can be incorporated in the design.
This occurs because aluminum has 5 times higher thermal conductivity than steel, and 8 times higher thermal diffusivity than typical P-20. This rate of heat transfer eliminates the need for costly conformal mold cooling. This also provides greater capacity yields per cavity than other processes.
What material is best for blow mold? ›Blow Molding Materials
In addition to HDPE blow molding, some of our most commonly recommended and requested materials and finishes include: Polypropylene (PP) Polyethylene (HDPE, MDPE, LDPE) Nylon (PA)
Since 1976, Custom Pack, Inc., has provided quality custom manufacturing, "packing" for both food and cosmetic grade products. The combined years of experience and capabilities among our staff can meet the specific packing needs of both the independent entrepreneur and the larger corporation.
Why are blow molds so popular? ›Why are blow molds so popular? Blow molds were the most popular in the 1950s-1970s. The past few years they've been really sought after and quite expensive. I think blow molds are so popular because they hold nostalgic value.
What are aluminum molds used for? ›Aluminum can be used to make molds for the injection molding process. Aluminum is an affordable material that is easy to work with and has many applications. However, aluminum molds, while slightly cheaper to produce, are considered inferior to steel molds.
How long do aluminum molds last? ›Aluminum molds could last for years and even decades while it is possible for class 101 molds to rapidly decay, due to inappropriate maintenance.
What material is used for aluminum molds? ›Aluminum mold can be designed depending on the abrasiveness of polymer material to produce from 100 K 1 million components. Aluminum alloys such as 7075, Alumold, QC-10 and Hokotol have a Brinell hardness range of 150-180 and Rockwell hardness range of B82-87.
Why are vintage blow molds so expensive? ›Sadly, there aren't many manufacturers of Christmas blow molds anymore. That's what makes the vintage blow molds so valuable. However, blow mold makers do still exist, and they continue to produce new blow molds for retailers who sell them online.
How long do blow molds last? ›According to Richard Bell, our Tooling Manager, “A well-maintained blow mold should last 15 – 20 years before the materials begin to fail beyond repair.”
Are blow molds making a comeback? ›
A new generation of old-fashioned blow mold decorations have come to town. Move over blow-up snowmen. This year, hollow plastic light-up figures are making a comeback and giving those inflatable fabric ornaments — the type with the fan inside — a run for their money.
Why are blow mold decorations so expensive? ›Sadly, there aren't many manufacturers of Christmas blow molds anymore. That's what makes the vintage blow molds so valuable. However, blow mold makers do still exist, and they continue to produce new blow molds for retailers who sell them online.
What are the uses of blow molding? ›Blow molding (or moulding) is a manufacturing process for forming hollow plastic parts. It is also used for forming glass bottles or other hollow shapes.
Which is better blow mold or Roto mold? ›Here's the bottom line: If you're producing fewer than 3,000 pieces of product per year, you might be better off using roto molding. But if your production volumes are higher, blow molding is the way to go because it can save 40 percent on per-piece cost.
Is blow molding cheaper than injection molding? ›Blow molding is generally cheaper than injection molding. This is because blow molded products are less complex, and therefore the required tooling is cheaper.