Prática de Shadowing: How Things Are Made | An Animated Introduction to Manufacturing Processes - Aprenda a falar inglês com vídeo
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Do you ever wonder how amorphous lumps of material are turned into the everyday products which surround us?
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Let's find out.
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In this video, we're going to talk about manufacturing processes.
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There are six main categories of manufacturing processes, which are forming, casting, molding,
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joining, machining, and additive manufacturing.
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Each one of these categories contains a large number of different manufacturing techniques.
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There are a lot of different factors which need to be considered when selecting the right manufacturing process.
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This includes the material you are working with, the geometry of the object, the number of parts you are producing,
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tool and material costs, and required levels of automation to name just a few.
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Let's look through each of the six categories in detail.
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Forming involves applying forces or pressure and plastically deforming the material to produce the desired shape.
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It is typically used for metals.
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Most forming processes can be done when the metal is either above or below its recrystallization temperature.
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This is known as hot or cold working.
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Hot working makes it easier to plastically deform the metal, but cold working causes strain hardening, which increases the strength of the material.
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Three common forming processes are forging, rolling, and extrusion.
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Modern forging is done using machines.
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In closed die, or impression forging, the metal is placed between top and bottom closed dies.
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Repeated strokes from the hammer are used to cause the metal to flow into the shape of the dies.
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Objects produced using forging can have improved mechanical properties compared to objects which are cast,
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but it can be difficult to achieve tight tolerances using forging, and the required equipment can be expensive.
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Extrusion is a continuous process which involves placing hot metal in a chamber
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and using a ram to force it through a die, producing a long object with a constant cross -section.
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Extrusion provides an excellent surface finish and can achieve very tight tolerances, but it is only suitable for producing two -dimensional shapes.
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Rolling is probably the most commonly used forming process.
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Plus, it involves passing metal between two or more rollers, which apply pressure and reduce thickness.
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More complex products like I -beams can also be manufactured by rolling.
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Rolling can result in improved mechanical properties and can be automated, which makes it good for large -scale production
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but tooling costs tend to be high
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and it can't be used to produce very complex shapes let's move on to the next category of manufacturing processes casting
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casting involves pouring molten metal into a mold
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and allowing it to solidify it is what we call a
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primary shaping process a secondary process such as machining is typically needed to achieve the desired surface finish.
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Like forming, casting is most commonly used for metals.
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Three common types of casting are die casting, sand casting, and investment casting.
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In die casting, molten metal is forced into reusable metal dies at high pressure.
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Once the molten metal has solidified, it is removed from the mold.
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die casting is mostly used for non -ferrous metals like aluminum
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and zinc which have low melting temperatures it provides an excellent surface finish
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and can achieve very tight tolerances but startup costs tend to be high
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so it is only really suitable for large production runs
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in sand casting a pattern is used to create a single -use mold from damp sand
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the sand is typically contained in two mold boxes called the cope and the drag
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molten metal is poured into the mold through a channel formed in the sand When the metal has solidified, the cast object can be removed from the sand.
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Sand casting can be used for a wide range of metals, including those with high melting temperatures.
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It can produce large and complex parts, and initial costs are very low, making it good for small production runs.
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However, it provides a poor surface finish and is not as accurate as other casting processes.
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The last casting process we will look at is investment casting.
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Several wax patterns of the same object are created and attached to a sprue.
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The wax tree is dipped into a slurry to create a ceramic mold.
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Heat is applied to melt out the wax.
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Molten metal is then poured into the ceramic mold.
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once the casting has cooled the mold is broken off.
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Investment casting is good for parts with complex geometry and can achieve tight tolerances, but it is an expensive and time -consuming process.
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Molding is very similar to casting.
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It involves shaping a liquid or pliable material using a mold.
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Most of the time molding is used for forming plastics.
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Typical molding processes are injection molding, compression molding, and blow molding.
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Let's look at the first two.
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Injection molding is the most commonly used manufacturing method for plastics.
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Polymer granules are fed into the hopper
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and a screw is used to pass the material through a heated cylinder before it is forced at pressure into the mold.
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Injection molding is mostly used for thermoplastics, which are polymers which soften when they are heated and harden when they are cooled.
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It is a very fast process and can be fully automated, meaning labor costs are low.
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But startup costs are very high due to the expensive molds, so it is really only cost effective for large production runs.
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Compression molding involves placing a precise amount of material into a mold.
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The mold is closed and pressure and temperature are applied.
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Compression molding is mostly used for thermosets, which are polymers which irreversibly harden
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when heated tooling costs are relatively cheap making it good for small production runs
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but it is quite a slow process
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and is not well suited for complex designs
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so far we have only looked at material deformation processes machining
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is a material removal process where a tool is used to
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remove material from a larger object it is often used for secondary shaping
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when the part has already been formed using a primary process like casting.
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Machining can be used for a wide range of materials, including metals, plastics, and wood.
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Examples of machining include drilling, turning, and reaming.
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Drilling is the cutting of a normal circular hole by pressing a rotating drill bit through a solid object.
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and turning is the use of a cutting tool to shape a rotating workpiece.
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Let's move on to the next category.
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Joining involves combining multiple separate components into a larger assembly.
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Like machining, joining is a secondary process.
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Welding, riveting, brazing, soldering, and fastening are all different types of joining processes.
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Welding uses extremely high heat to fuse distinct metal parts together.
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Unlike soldering and brazing, the base metal melts during welding.
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The final category is additive manufacturing, which involves adding material to build up the desired object, typically one layer at a time.
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3D printing, selective laser sintering, and VAT polymerization are examples of additive manufacturing techniques.
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For 3D printing, a computer is used to successfully build up an object layer by layer.
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3D printing is a slow process, and the range of materials which can be used is limited.
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As a result, it tends to be used for prototyping rather than for mass production.
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That's it for this introduction to manufacturing processes.
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Please leave a comment to let me know what you think, and don't forget to subscribe if you haven't already.
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Vocabulário e dicas de fala para esta lição
Esta aula de conversação de nível C1 usa o vídeo “How Things Are Made”. As palavras que mais se repetem: metal, casting, material, mold, process. Este vídeo tem 92 frases e 1229 palavras para praticar shadowing. A fala dura 10:17. O falante mantém um ritmo estável de cerca de 120 palavras por minuto, confortável para o shadowing. Apenas 73% das palavras estão entre as 3.000 mais comuns do inglês, por isso o vocabulário é exigente.
Vocabulário principal deste vídeo
As 15 palavras mais avançadas do vídeo, com pronúncia e significado:
| Palavra | Pronúncia | Significado |
|---|---|---|
| mold substantivo | /moʊld/ | mofo, bolor |
| melt verbo | /mɛlt/ | derreter, fundir |
| forge substantivo | /fɔɹd͡ʒ/ | frágua, forja |
| tolerance substantivo | /ˈtɑ.lə.ɹəns/ | tolerância |
| additive substantivo | /ˈæd.ɪ.tɪv/ | aditivo |
| extrusion substantivo | extrusão | |
| solidify verbo | /səˈlɪdɪˌfaɪ/ | solidificar |
| weld verbo | /wɛld/ | soldar |
| harden verbo | /ˈhɑɹdn̩/ | endurecer |
| polymer substantivo | /ˈpɑ.lɪ.mɚ/ | polímero |
| compression substantivo | /kəmˈpɹɛʃ.ən/ | compressão, compactação |
| injection substantivo | /ɪnˈd͡ʒɛk.ʃən/ | injeção |
| drill substantivo | /dɹɪl/ | furadeira, berbequim |
| automate verbo | /ˈɔ.təˌmeɪt/ | automatizar |
| braze verbo | /bɹeɪz/ | brasar |
Phrasal verbs que você vai ouvir
| Palavra | Significado |
|---|---|
| break off verbo | separar |
| find out verbo | descobrir |
Gramática neste vídeo
As estruturas que o falante mais usa, com as palavras exatas do vídeo:
| Estrutura | No vídeo |
|---|---|
| Voz passiva be + particípio passado — o foco está no que acontece, não em quem faz | are turned · be considered · can be done |
| Orações relativas who / which + oração — informação extra sobre uma pessoa ou coisa | processes, which are · objects which are · automated, which makes |
| Present perfect have/has + particípio passado — uma ação passada que ainda importa agora | have improved · has solidified · has cooled |
Pronúncia para ficar de olho
O falante usa 4 contrações e formas reduzidas, como can't, don't, haven't. Diga-as na forma curta, do jeito que você ouve.
- Os sons de “sh” e “zh”: compression /kəmˈpɹɛʃ.ən/, injection /ɪnˈd͡ʒɛk.ʃən/, deformation /ˌdɛfəˈmeɪʃən/, polymerization /ˌpɒl.ɪ.məɹ.aɪˈzeɪ.ʃən/, automation /ˌɔ.təˈmeɪ.ʃən/
- Palavras longas — acerte a sílaba tônica: solidify /səˈlɪdɪˌfaɪ/, geometry /d͡ʒiˈɑ.mə.tɹi/, deformation /ˌdɛfəˈmeɪʃən/, polymerization /ˌpɒl.ɪ.məɹ.aɪˈzeɪ.ʃən/, automation /ˌɔ.təˈmeɪ.ʃən/
Sons difíceis para falantes de português:
- Consoante final — sem acrescentar um “i” depois: mold /moʊld/, melt /mɛlt/, weld /wɛld/, automate /ˈɔ.təˌmeɪt/, rotate /ˈɹoʊ.teɪt/
- /l/ final — a língua toca o céu da boca, não vira “u”: drill /dɹɪl/, granule /ˈɡɹæn.jul/, pliable /ˈplaɪəbəl/, dimensional /daɪˈmɛn.ʃə.nəl/
- /h/ — um sopro suave, diferente do “r”: harden /ˈhɑɹdn̩/, grasshopper /ˈɡɹæsˌhɑpəɹ/
Como praticar com este vídeo
- Ouça o vídeo inteiro uma vez sem falar e anote as palavras que você não conhece.
- Faça shadowing frase por frase na velocidade normal, repetindo cada uma até o seu ritmo ficar igual ao do falante.
- Grave a sua voz e compare com o original, prestando atenção a palavras como mold, melt, forge.
O que é a Técnica de Shadowing?
Shadowing é uma técnica de aprendizado de idiomas com base científica, originalmente desenvolvida para o treinamento de intérpretes profissionais. O método é simples, mas poderoso: você ouve áudio em inglês nativo e repete imediatamente em voz alta — como uma sombra seguindo o falante com 1-2 segundos de atraso. Pesquisas mostram melhora significativa na precisão da pronúncia, entonação, ritmo, sons conectados, compreensão auditiva e fluência na fala.