How do you control volume when casting?

Casting allows you to stream media content like videos, music, and photos from your smartphone or computer to external devices like smart TVs, speakers, and other screens. Being able to control the volume when casting is important for several reasons:

First, the external device you are casting to may have a different maximum volume range than your smartphone or computer. Having volume control allows you to adjust the sound to an optimal level for the environment and external device.

Second, controlling volume directly from your casting device is more convenient than having to manually adjust volume on the external device. This is especially true if the external device like a smart TV is located across the room.

Finally, being able to control casting volume allows you to easily pause or mute if needed without disrupting the casting session. Overall, volume control provides a better user experience when casting media to various devices and screens.

Pre-Casting Volume Adjustments

One way to control volume when casting is to make adjustments in the wax or resin before the actual casting process. This involves modifying the model or pattern itself to increase or decrease the overall size and dimensions [1]. For example, if the desired volume is smaller, the wax model can be scaled down before making the mold. If a larger volume is needed, the model can be enlarged.

Adjustments at this stage allow the volume to be fine-tuned before committing to the full casting process. Changing dimensions in the wax or resin is often an easier and more efficient way to control volume compared to adjustments after molding or casting. It also avoids wasting materials and effort on an improperly sized casting. Pre-planning the volume at the model stage can help achieve the required size right from the initial casting.

Spruing

The sprue is the main channel through which molten metal flows to enter the mold cavity. Proper sprue design is critical for controlling volume when casting. As explained in this article from Stuller, “There are four functions of a sprue: 1. Secure pattern in position. 2. Provide channel for the elimination of wax. 3. Provide channel for the controlled flow of metal. 4. Allow gases generated during casting to escape” (Stuller). The size and shape of the sprue affects the velocity and turbulence of the molten metal, which impacts volume control.

Larger diameter sprues allow metal to flow quickly into the mold with less resistance, which can lead to excess volume and overflow defects. Smaller sprues restrict flow, slowing the fill and potentially leading to misruns if the sprue is too thin. Tapered sprues from top to bottom help control velocity while allowing gases to escape. The angle of the sprue also affects flow; vertical sprues promote smooth laminar flow while angled sprues introduce more turbulence. Overall, carefully designing the sprue system provides a way to regulate the speed and direction of molten metal entering the mold, critical for controlling fill volume.

Venting

Venting is an important process in controlling volume when casting metals. It allows gases to escape from the mold as the metal solidifies. Without proper venting, gases can get trapped in the casting and cause defects like pores and cracks. Proper venting is achieved through the design of vents and risers in the mold.

Vents provide a path for gases to escape the mold cavity. They are incorporated into the mold design by adding small channels that connect the cavity to the atmosphere. Vents need to be placed at the highest points in the mold cavity so that air can freely rise up and out as the metal fills the mold. Multiple vents may be required on larger castings to allow gases to fully vent.

Another key aspect of venting is the size of vents. Vents need to be wide enough to allow gases to escape, but not so wide that liquid metal can flow out. Optimal vent size depends on factors like the metal being cast and the size of the cavities. Proper vent sizing helps control the flow of gases while retaining the full volume of liquid metal in the mold.

In summary, incorporating well-designed vents enables gases to escape the mold cavity during casting. This prevents gas porosity defects and allows the final casting to achieve full volume. Vent position at the highest points and appropriate vent size are key considerations when designing vents.

Gating

The gating system is a crucial part of controlling volume when casting metal. The gating system includes the sprue, runner, and ingates that deliver molten metal into the mold cavity. Proper gating design helps ensure complete mold filling while avoiding defects like porosity and turbulence (https://vietnamcastiron.com/gating-system/).

Several aspects of gating design impact volume control. First, the size and shape of the sprue and runner channels regulate metal flow. Wider, more tapered channels allow faster flow rates and higher volume delivery. Conversely, narrower channels restrict flow. The number of ingates and their size also control volume – more/larger ingates fill the mold faster (https://precision-casting.co.id/gating-system/).

Additionally, the gating ratio, or ratio of gating channels to casting volume, influences fill rate and volume. Higher gating ratios increase volume flow into the mold cavity for a given metal temperature and viscosity. Proper gating design is critical for controlling the speed and completeness of mold filling.

Risers

Risers, also known as feeders, are cylindrical channels built into the mold that allow molten metal to flow into them during casting. They act as reservoirs that feed the casting as it solidifies and shrinks, compensating for volume change. As the casting cools and shrinks, the riser remains molten and feeds liquid metal into the shrinking casting to prevent voids and porosity (Wikipedia, 2022).

Risers are placed at the thickest and last solidifying sections of the casting to compensate for volume changes during solidification. They must stay molten while the casting solidifies in order to be effective. Design considerations for risers include their size, shape and location. Ideally, risers solidify last, after the casting is completely solidified (Haworth Castings, 2016).

The main purpose of risers is to feed liquid metal to the casting as it shrinks to compensate for volume change. Well-designed risers can minimize shrinkage defects like voids and porosity in castings.

Pouring Temperature

The pouring temperature of the molten metal has a significant effect on the final volume of the casting. As the liquid metal cools from the pouring temperature to the freezing temperature, there is natural shrinkage that occurs (The Metal Casting Operation). Higher pouring temperatures lead to more shrinkage and lower final casting volume. This is because there is a greater temperature difference between the initial pouring temperature and freezing point. Conversely, lower pouring temperatures result in less shrinkage and higher final volumes.

To control volume through pouring temperature, foundries aim for the lowest possible temperature that still allows for proper filling of the mold. Lower pouring temperatures, closer to the freezing point, minimize shrinkage. However, the pouring temperature cannot be too low, or else the metal will solidify before filling the mold properly. An optimal pouring temperature – not too high and not too low – is essential for controlling the final casting volume (Pouring and temperature control).

The optimal pouring temperature depends on the metal being cast. Foundries carefully monitor and control pouring temperatures to account for the shrinkage behavior of different alloys. Fine tuning the pouring temperature is one of the primary methods used to adjust final casting volumes.

Mold Materials

The type of material used to make the mold can greatly affect how the molten metal shrinks and cools inside the mold cavity. Different mold materials will expand and contract at varying rates as the hot metal is poured in. This differential expansion/contraction of the mold vs. the cooling metal will impact the final casting dimensions and quality.

Some key factors to consider with mold materials:

• Metal molds like steel and iron have very low coefficients of thermal expansion, so they resist expanding as the hot metal is poured in. This can lead to the casting shrinking more inside the mold cavity and create dimensions smaller than intended.
• Silica sand is an extremely common mold material that has a higher coefficient of thermal expansion. The sand mold will expand more as the metal shrinks, helping counteract shrinkage.
• Specialized expanding mold materials like Ashland’s Pep Set products contain additives that greatly increase thermal expansion. These purposefully expand against the shrinking hot metal to maintain truer dimensions.
• Highly precise ceramic molds have very controlled, uniform thermal expansion behavior. This predictability allows them to hold extremely tight tolerances if properly designed.

Overall, understanding the thermal expansion traits of the chosen mold material is crucial. Proper selection, design, and process control allows mitigating shrinkage issues for quality castings.

Final Adjustments

Once the metal has been cast, there are still some final adjustments that can be made to control the volume. Filing, grinding, and machining the casting can remove excess material and reduce the overall size and weight. According to a Reddit thread, controlling volume when casting to devices like Chromecast can be challenging, as the default volume controls are tied to the device or app rather than the phone or tablet casting the content (source). The Cast Companion Library for Android provides methods for implementing custom volume controls that can override the default behavior (source). Similarly for Home Assistant, workarounds involve saving and restoring the volume level when turning casting on and off (source).

In summary, while adjustments to the mold and pouring process account for much of the volume control, additional tweaks can be made after casting through mechanical means or by overriding default software volume settings.

Conclusion

In summary, there are several key ways to control the volume when casting:

During pre-casting, adjust the volume levels in the device settings and on the casting app. Optimize spruing, venting, gating, and risers in the mold design to control flow rates and reduce turbulence. Pour at the proper temperature for the mold material. Select mold materials like sand that absorb sound. Make final tweaks by adjusting software settings and the physical environment.

Controlling volume starts before pouring and continues with thoughtful mold design. Materials, temperatures, and settings can then be used for final adjustments. Following these casting volume control best practices will help achieve the desired auditory results.