A suitable ‘ice melting kit’ is available from the supplier: Timstar. 11-14. The Institute is a charity registered in England and Wales (no. This is because, when you touch a piece of metal, energy conducts away from your fingers into the metal, lowering the temperature of your fingers. Show that the two blocks are both at room temperature at the start, and observe the rapid drop in temperature of the metal block. So you could use thermometers to test the temperatures of different objects and materials in the room. In the past, one of the biggest roadblocks to replacing metal parts with plastic was that plastic, while much lighter, could not compete with the strength characteristics of metal. This would happen if plastic had a low specific heat capacity. Source – By Nicoguaro – Own work, CC BY 4.0. Manganese: 7.81: lowest thermal conductivity of any pure metal Marble: 2.07 … Practical Activity © 2020 IOP All rights reserved. You may then wish to take the discussion to a deeper level. Diamond atoms are composed of a simple carbon backbone that is an ideal molecular structure for effective heat transfer. Note that there is a complication to this analysis which we have avoided mentioning so far. Plastics are good insulators so, even though the plastic is at a lower temperature than your fingers, little energy conducts to the plastic and it feels warm. The heat transfer characteristics of a solid material are measured by a property called the thermal conductivity, k (or λ), measured in W/m.K. PLASTIC: Heavy weight equals heavier costs. This is because complex designs, shapes, branding, and surface textures can be incorporated directly into a part’s tooling. This method and the nature of thermoplastic also offer a much larger scope of design complexity capabilities and options that are unavailable to metal manufactured parts (see Thermoforming Material Selection: 5 Ways Thermoplastic Materials Can Influence Product Appearance). Whereas unfilled thermoplastics have a thermal conductivity of around 0.2 W/mK (Watts/meter-°Kelvin), most thermally conductive plastic compounds typically have 10 to 50 times higher conductivity (1-10 W/mK). You could ask your students to explain why the temperature-time graphs for the two blocks are curved (they are roughly exponential). (There are a multitude of grade and alloy variations of steel and aluminum, and there are just as many diverse formulations of plastic material. Data for these materials can be found on thermoplastic material manufacture websites. 15 Resources. The thermal conductivity of typical steel is 20 W/(m.K). Note: There are plastic belt materials which are self-extinguishing. However, innovations in both plastic materials and process capabilities, coupled with changes in industry demands have closed many of the physical and cost performance gaps that once existed between metal and plastic. Diamond is the leading thermally conductive material and has conductivity values measured 5x’s higher than copper, the most manufactured metal in the United States. Below are 5 key comparisons to consider for METAL vs. The reason for this is that the rate of transfer of energy from the block to the ice decreases as the temperature difference between them decreases. $\endgroup$ – Jens Aug 29 '16 at 20:33 But what is necessary? It is also resistant to corrosion and permeable for … Alternatively, attach a temperature probe to each block and observe how their temperatures change. Metal versus plastic is an old argument and it’s likely that you or your company have previously compared them for past projects. If you were to take a part made from steel and compare it to the same part made from thermoplastic, the plastic part could be more than 6 times lighter. Whether you’re trying to meet a deadline or fill orders for an increase in demand, time to market can be an essential factor to the success of any project. 14-16. Hence it is best to start the demonstration by asking your students to feel the two blocks so that they may be misled by this experience. The thermal conductivity factors indicate that the metallic materials will outperform the plastic materials. Fuel efficiency, maintenance costs, logistics, installation – all see significant cost reductions in tandem with a decreased part weight. Then repeat the demonstration with electronic thermometers monitoring the temperatures of the blocks as the ice cubes melt. Pass the metal and plastic blocks around the class; ask your students what differences they observe. This is because, when you touch a piece of metal, energy conducts away from your fingers into the metal, lowering the temperature of your fingers. Take that same part, now manufactured with aluminum, and the plastic version would be approximately half the weight. This means that plastic needs more "coldness" to lower temperature initially but once equilibrium is reached, plastic pulls ahead. Metals can conduct (transfer) heat much faster than plastics. In addition to greatly increasing production and lead times as mentioned above, as part design complexity increases, part cost increases at an exponential rate. Ask for predictions as to what will happen. Referencing the chart below, you can see that this is a major advantage that plastic has over metal. 293851) and Scotland (no. Request a free Productive Plastics’ Metal to Plastic Thermoforming Comparison and Conversion Guide (PDF) from Productive Plastics. The film below shows how to carry out this demonstration, together with typical results. Ice cubes are placed on metal and plastic blocks; the cube placed on metal melts much more quickly than the cube placed on plastic. When referencing the chart below note that examples of thermoplastic reside in the composite and polymer categories and that this data may not include all thermoplastic material products, many of which are specially formulated to compete with metal and alloys in strength and stiffness. Shaping a metal part can require die work, welding, grinding, rework, or bending on each individual part produced to achieve design specifications and desired look. With a dramatically less labor intensive process, plastic thermoforming can save production time, energy, labor, and cost compared to manufacturing components from metal processes. 14-16, A selection of home experiments and simulations that are suitable to use remotely with your students, Remote teaching support Then show that the ice on the metal block melts more quickly, and discuss the reasons. Heavy weight equals heavier costs. A test collector was constructed employing the six tubing materials for the implicit purpose of comparing their ability to conduct heat in comparison to the thermal conductivity rates. Heavy vs thin gauge plastic thermoforming – what’s the difference. Experiments in this collection explore more subtle ideas: heating by friction, the... For 14-16 Explain that you are going to place identical ice cubes on each block. There are no safety problems with this demonstration. Generic Limestone R is relatively pure polycrystaline calcite, solidity is the quotient of the solid grain volume divided by the bulk volume and K is thermal conductivity in W⋅m −1 ⋅K −1. • Part finishing (bonding attachment points). Many industries, such as aerospace, medical devices, and mass transit, are realizing the potential of the updated advantages of replacing large scale, interior, or enclosure metal parts with plastic materials and manufacturing processes, such as thermoplastic materials and the plastic thermoforming process. The rate at which energy is transferred to the ice depends on both the conductivity of the block and its heat capacity. This is shown not to be the case by when a temperature probe is used. SC040092), Metal and plastic blocks of identical dimensions, 2 temperature probes with displays (optional). One firm, Cool Polymers, offers products with 100 to 500 times the conductivity of a base polymer (10-100 W/mK).

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