Month: November 2022

The process of casting manufacturing involves the pouring of a molten metal into the cavity of a mold designed to produce a specific shape, which is then allowed to cool and harden. After the molten material solidifies, the newly-formed workpiece is extracted from the mold and subjected to finishing processes that results in the final product. Metal casting, including aluminum casting, is often used to create complex hollow and solid shapes. Casting is used for various industrial applications, including those in the aerospace and automotive industries.

Below we cover three popular casting processes – Sand Casting, Die Casting, and Investment Casting. The choice of casting must be made based on various considerations related to engineering, design, manufacturing, and cost.

Sand Casting

Sand casting usually depends on materials that are silica-based. These can include naturally-bonded or synthetic sand. The sand used for casting is typically spherical, finely ground grains that are packed together tightly into a smooth molding surface. This form of casting tends to reduce the possibility of cracking, tearing, and other defects by introducing shrinkage and flexibility into the cooling process. Clay may be added to strengthen the sand, helping to strengthen the bond between particles. Sand casting is often used to produce engine blocks.

The level of accuracy produced with sand casting is generally lower than with other methods. The products yielded from this process, including aluminum casting with the sand casting method, also tend to have a comparatively rougher surface finish.

Die Casting

The die casting process molds materials under high pressure and is often used for non-ferrous metals and alloys such as aluminum, copper, zinc, and tin. A lubricant is coated onto the surface of the mold to keep the temperature of the die under control and make material extraction from the mold easier. With this casting method, molten metal is placed into the die under high pressure, which is maintained until the solidification of the workpiece occurs.

The benefits of die casting, including when performed for aluminum casting needs, such as uniform design, high components dimensional consistency, closer near net shape and size tolerances, and less of a need for machining after the casting phase.

Die casting does have high tool costs, which means high volume production runs will increase its cost-efficiency. Also, products made with die casting are not often structural in nature since it is challenging to ensure the mechanical properties of a die-cast product.

Investment Casting

Investment casting utilizes a disposable wax pattern for each part cast. The wax is placed into a mold. It is then removed and covered with refractory material and a binding agent. This is often done in multiple stages to create a thicker and thicker shell. Various patterns are put together onto common sprues. After the shells have hardened, the patterns are inverted and then placed into ovens for heating to remove the wax. Then, the molten metal is emptied into the remaining shells. The resulting piece which has hardened reflects the wax pattern shape. The refractory shell is then removed to display the hardened casting. This method of casting is often utilized in the power generation, automotive, and aerospace industries, including for turbine blades.

Investment casting benefits include:

• Exceptionally precise and accurate dimensional results.
• Ability to cast ferrous and non-ferrous metals
• Produces exceptional quality surface finish and component details
• Can produce parts with complex geometries and thin walls

The quality surface finish produced through investment casting (for metal and aluminum casting) can compensate at times for the higher expense associated with this casting method.

Sand Casting vs. Die Casting

The mold types used for each method are different. Sand casting uses sand mold, while die casting uses metal molds. Dies casting is more ideal for parts that require dimensional accuracy and is ideal for higher production runs.

Sand Casting vs. Investment Casting

Sand casting produces a rougher surface finish and can produce net shapes within 1/4 of an inch. Investment casting produces excellent surface finishing and is the optimal choice for highly complex designs. Sand casting offers greater versatility with weight and size capabilities than investment casting.

Die Casting vs. Investment Casting

The differences between die casting and investment casting include:

• Die casting uses reusable molds while investment casting uses disposable molds for each new cast.
• Die cast parts may require some post-processing in order to achieve desired finishes and dimensions, while investment casting generally requires little to no additional processing.
• Investment casting is ideal for production runs in the low to medium volume range, while die casting is more suitable for production runs in the high volume range.
• Die casting may only be used for non-ferrous metal casting, while investment casting can be used on both ferrous and non-ferrous metals.

When it comes to aluminum casting and other metal casting, the casting methods mentioned above have their own unique benefits and drawbacks that make them ideal for certain manufacturing requirements.

The significant benefit to using any casting method is you end up with a part that is close in size and weight to the end product of your part. Yes, it will involve finish machining but it saves you a both machining time and metal over machining your part from a solid piece of Aluminum, whether from a wrought or cast aluminum plate.

At Howard Precision Metals we often get asked what is more cost effective, machining a part from a solid block or from a casting? As mentioned above the tooling for a cast part needs to be amortized over the run quantities. If your quantities are low, it normally does not justify tooling up a mold for casting. However, if you have high run quantities that will keep increasing over the lifetime of a part, a casting should always be considered. Should you need Aluminum cast or wrought blocks to machine your prototypes from prior to casting Howard Precision Metals is here to help.

To learn about the standard and custom aluminum products we offer, including custom aluminum extrusions, give us a call today at 800.444.0311 or request a quote.

In today’s manufacturing environment, we all have a lot on our plate. Therefore, it is even more important to choose the right metal supplier. You need that supplier to meet your needs from a quality, delivery, and competitive perspective.

There are many quality metal distributors to choose from, but understanding the difference comes down to a respect for each other and good communication. In order to be the best supplier, there needs to be a two-way street, and if you expect clear and timely communication from your metal supplier, you must first start by giving them all the information they need.

Include metal specifications on your RFQ

All metals are produced to certain specifications that typically define their chemistry, physical properties requirements, method of production, and even country of origin of the mill producer. Today, a test report, or mill certification will often state the country the alloying elements are mined from as well. Some governments limit producers from supporting countries that conflict with their beliefs. It is always good to include every specification you have, as well as any alternative specifications that can also be used. Giving your supplier all the possible options will allow them to quote you the most competitive price.

Tell them when you need the metal.

As we all struggle with availability of some metals due to both a limited global supply chain and shortage of manufacturing workers, it is important that you are clear from the beginning with your delivery needs. A quality metal supplier will always be honest with you if they are unable to meet your delivery. Sometimes, if the requirement is so large, they may have to split the shipments or tell you they can only supply a given amount of your needs. At Howard Precision Metals, a distributor of Aluminum Plate, bar and extruded products, we pride ourselves on being transparent. We would rather lose an order than lose a customer’s trust by promising a delivery we can’t meet. In addition, there are many logistic challenges facing your metals suppliers today, due to the CDL driver shortages. If material does not arrive to your supplier on time, causing your order to not ship as promised to you, a good supplier will advise you before you even realize it is late.

Specify your required tolerances.

Not all producers of metal are created equal. We are dependent on a global market for most of our metals. Whether Carbon Steel, Stainless Steel, Aluminum, or Red Metals, there is a limited number of producers here in the United States.

Elevated tolerance standards have been set in the US that some foreign producers are not even aware of, so don’t assume you are getting the same tolerances from producer to producer, or metals suppliers. The most important tolerances to understand and communicate are thickness and flatness for rolled or cast Aluminum plate, and straightness, twist, and dimensional tolerances for extruded Aluminum bar. If you do not know what to expect, you can always give your metals supplier your finished dimension after machining along with your typical machining allowance required. In Aluminum there are many producer tolerance specifications that guarantee their product to have a plus side tolerance. That does not guarantee the material will clean up to the nominal dimension, it only guarantees that the dimensions will be plus. If your plate is .001” over the nominal dimension, it is considered plus but does not allow a machinist to attain 100% clean-up to the representative surface. It is important to communicate your required tolerance to your supplier to always insure they meet your needs.

Call out the trade name if specified on your drawing

In the metals industry there are many trade names that the producing mills have branded their products with. Aluminum Cast Tool and Jig Plate is a perfect example. Mic-6 is the grandfather of CT&J Plate. You are likely to see it on blueprints from the 1950s.

The way it is produced is different from other Cast Aluminum Plate products, so if you see it on a blueprint and it does not say “or alternative”, you should call out Mic-6 to your supplier and indicate “Must be Mic-6”. The primary base metal of Mic-6 is a 7000 series alloy, unlike other cast products that are 5000 series. There is a reason that Mic-6 has stood the test of time and is specified still today on many blueprints. It has superior flatness and dimensional stability that allows a machinist to produce extremely tight tolerance parts. When an engineer specifies Mic-6 on a drawing, he is doing it for a reason. So, the next time you see a brand name specified on a blueprint, be sure to put that on your RFQ, so you are sure to get it.

Communicate your packaging and receiving requirements

As manufacturing companies advance, there are requirements that your metals supplier needs to know. Let’s start with packaging. Do you have products that need to be skidded separately to speed up flow at each machine, or possibly at a cell of several machining centers?

Packaging everything separately may cost a little more, but how much time does it save your people? In today’s lean environments, nobody wants to touch parts more than they have to. How about packaging requirements that ensure the surface of your product is protected from damages during shipment, and lastly, make sure your metal supplier is aware of your maximum skid weight and unloading capabilities.

These specifications are typically asked and noted into your metal supplier’s system when you first open an account, but when was the last time you reviewed it with your supplier. There are updates that could be saving your company money or improving your flow.

In any type of business, communication is key to a successful relationship. The topics discussed in this blog may sound simple or overstated, but in today’s fast paced environment, we often forget to include a key piece of information. You are extremely lucky if you have a customer service rep at your metals supplier that you have been working with for years and knows your needs when you forget to include something. However, even an experienced rep should not assume.

Phone calls and emails take time to confirm your required specifications, slowing down the process and adding extra steps. In conclusion, to have a successful relationship with your metal’s supplier, review your RFQ and or purchase order before you send it.

Make sure all the information you need to be met is shared on you PO. At Howard Precision Metals, we take pride in providing our customers with their specified requirements and understanding what it takes to meet their needs. If you need Aluminum Plate, bar, or extruded shapes, saw cut to precise tolerances, Howard is the metals supplier for you.