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09/06/2024 | News release | Distributed by Public on 09/06/2024 10:37

Aluminum Mold Tooling for Injection Molding

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September 6, 2024

Aluminum Mold Tooling for Injection Molding

By Ben Wilson
Injection Molding Product Leader at Protolabs

A part's journey through injection molding hits an early form in the road when the customer must decide between aluminum and steel tooling. Choosing a path is based primarily on quantity demands. If you are producing quantities north of a million parts, steel tooling and a capital investment of more than $50,000 is necessary.

If your part volumes don't stretch into the millions, aluminum tolling at a fraction of the cost is likely the path for you. In bypassing the high-volume paradigm-large investment, long wait times, and above all, inflexibility-aluminum tooling allows product developers to be nimble.

The aforementioned benefits of aluminum are in part due to the materials machinability. Compared to steel, aluminum is softer, meaning it can be CNC machined for molding much faster than steel. Less machine time equals less cost. Aluminum is capable of molding production quantities of about 10,000 parts as a rule of thumb, but quantities are often much higher. Mold life is dependent on the material type and geometry. Still, it will likely need to be replaced for before a steel mold would.

In general, aluminum tooling is the ideal choice if part volumes don't stretch into the millions, if you need on-demand production parts within days, and if you're looking to avoid risky tooling investments before your part design is truly validated.

Key Benefits of Aluminum Molds

Aluminum tolling has several advantages. Molds begin around $1,500 and can be delivered in seven days or less. Steel tooling, comparatively, works on a larger lead time.

Aluminum tooling produces production quantities of at least 10,000 parts, but often much more. At Protolabs, customers can choose either prototyping or on-demand production for quantities and corresponding price point to fit their needs (more on that later).

Aluminum molds are also capable of many of the features customers expect with production tooling, including:

  • Single and multi-cavity tooling: 1-, 2-, 4-, and 8-cavity molds are possible depending on part size and complexity.
  • Expansive materials library: thermoplastic and thermoset materials identical to that of high-volume production materials are available. More than 100 different materials can be used including ABS, polycarbonate (PC), polypropylene (PP), liquid crystal polymer (LCP), polyoxymethylene (POM)
  • Beneficial material properties: The thermal conductivity of aluminum allows for improved heat dissipation, reducing the need for messy cooling lines.

An additional cost savings, aluminum molds also remove the need for maintenance feeds with damage to the mold covered over its lifetime.

Design Considerations for Aluminum Molds

Part Finish

Choosing the correct surface finish for your part's application will prevent unnecessary expense. If part cosmetics are critical, a smooth SPI-A2 finish requires mold cavity surfaces to be hand-polished with diamond buff to 1-2 Ra. This drives up the cost of mold manufacturing and increases in lead time. If aesthetics is not a concern, PM-F0 is an as-machined surface that will probably show some tool marks but is the least expensive. Below you will find the full range of surface finishes offered at Protolabs:

Surface Finish Specification Description
PM-F0 Non-cosmetic, finish to Protolabs' discretion
PM-F2 Non-cosmetic, EDM permissible
PM-F1 Low-cosmetic, most toolmarks removed
SPI-C1 600 grit stone
SPI-B1 600 grit paper
SPI-A2 Grade #2 Diamond Buff
PM-T1 Light bead blast
PM-T2 Medium bead blast

Draft for Part Ejection

Whether aluminum or steel tooling, adding draft to your mold is required to improve the moldability of your part. Without it, parts may have a poor surface finish, and may bend, break, or warp due to the molding stresses caused by the plastic cooling. By adding a taper to the faces of the part, draft prevents scraping as the part is ejected out of the mold.

Wall Thickness

Each thermoplastic family has a recommended minimum wall thickness. Following those guidelines will help prevent warp and sink during cooling. A general rule for wall thickness is somewhere between 0.040 in. to 0.140 in. (1 to 3.5mm), applied consistently across the entire part.

Add Radii to Corners

Aluminum molds are CNC machined at Protolabs, which is quick and effective; however, the end mills used make machining sharp internal corners difficult. Furthermore, sharp corners on any mold create stress and weaken structural integrity. With that, generous use of radii (rounded edges or vertexes) in part design is recommended.

Aluminum Tooling at Protolabs

Protolabs offers two service-level tooling options capable of meeting unique needs during the product development process.

Prototyping offers a lower price point for limited qualities, while part price is higher. On-demand manufacturing offers a longer mold life and is best when production will be needed for multiple years at higher volumes for end-use parts. View this page to compare our tooling options for injection molding.

If you have any questions, don't hesitate to contact our applications engineers for help at 877-479-3680 or [email protected].

If you have any issues getting your guide, click here to download.

Definitive Guide to Injection Molding

This complete reference guide walks you through everything from quoting, design analysis, and shipment to best practices that ensure your model is optimized for molding.

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United States of America Afghanistan Åland Islands Albania Algeria American Samoa Andorra Angola Anguilla Antarctica Antigua and Barbuda Argentina Armenia Aruba Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bermuda Bhutan Bolivia, Plurinational State of Bonaire, Sint Eustatius and Saba Bosnia and Herzegovina Botswana Bouvet Island Brazil British Indian Ocean Territory Brunei Darussalam Bulgaria Burkina Faso Burundi Cambodia Cameroon Canada Cape Verde Cayman Islands Central African Republic Chad Chile China Christmas Island Cocos (Keeling) Islands Colombia Comoros Congo Congo, the Democratic Republic of the Cook Islands Costa Rica Côte d'Ivoire Croatia Cuba Curaçao Cyprus Czech Republic Denmark Djibouti Dominica Dominican Republic Ecuador Egypt El Salvador Equatorial Guinea Eritrea Estonia Ethiopia Falkland Islands (Malvinas) Faroe Islands Fiji Finland France French Guiana French Polynesia French Southern Territories Gabon Gambia Georgia Germany Ghana Gibraltar Greece Greenland Grenada Guadeloupe Guam Guatemala Guernsey Guinea Guinea-Bissau Guyana Haiti Heard Island and McDonald Islands Holy See (Vatican City State) Honduras Hong Kong Hungary Iceland India Indonesia Iran, Islamic Republic of Iraq Ireland Isle of Man Israel Italy Jamaica Japan Jersey Jordan Kazakhstan Kenya Kiribati Korea, Democratic People's Republic of Korea, Republic of Kuwait Kyrgyzstan Lao People's Democratic Republic Latvia Lebanon Lesotho Liberia Libya Liechtenstein Lithuania Luxembourg Macao Macedonia, the Former Yugoslav Republic of Madagascar Malawi Malaysia Maldives Mali Malta Marshall Islands Martinique Mauritania Mauritius Mayotte Mexico Micronesia, Federated States of Moldova, Republic of Monaco Mongolia Montenegro Montserrat Morocco Mozambique Myanmar Namibia Nauru Nepal Netherlands New Caledonia New Zealand Nicaragua Niger Nigeria Niue Norfolk Island Northern Mariana Islands Norway Oman Pakistan Palau Palestine, State of Panama Papua New Guinea Paraguay Peru Philippines Pitcairn Poland Portugal Puerto Rico Qatar Réunion Romania Russian Federation Rwanda Saint Barthélemy Saint Helena, Ascension and Tristan da Cunha Saint Kitts and Nevis Saint Lucia Saint Martin (French part) Saint Pierre and Miquelon Saint Vincent and the Grenadines Samoa San Marino Sao Tome and Principe Saudi Arabia Senegal Serbia Seychelles Sierra Leone Singapore Sint Maarten (Dutch part) Slovakia Slovenia Solomon Islands Somalia South Africa South Georgia and the South Sandwich Islands South Sudan Spain Sri Lanka Sudan SuriName Svalbard and Jan Mayen Swaziland Sweden Switzerland Syrian Arab Republic Taiwan, Province of China Tajikistan Tanzania, United Republic of Thailand Timor-Leste Togo Tokelau Tonga Trinidad and Tobago Tunisia Turkey Turkmenistan Turks and Caicos Islands Tuvalu Uganda Ukraine United Arab Emirates United Kingdom United States Minor Outlying Islands Uruguay Uzbekistan Vanuatu Venezuela, Bolivarian Republic of Viet Nam Virgin Islands, British Virgin Islands, U.S. Wallis and Futuna Western Sahara Yemen Zambia Zimbabwe
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