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Assignment 2
MechanicalDesignProcess(機械設計過程)
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PG4 Materials and Processes(材料與工藝)
4.1 Cost Versus Time Versus Specification(成本與時間與規格)
we’ll return to cost considerations of the design. With that reestablishment of this design “touchstone,” we’ll do with more “building blocks” that will be available to the designer to determine the best materials and processes for their enclosure parts.
我們將回到設計的成本考慮因素。 通過重新設計“試金石”，我們將
設計更多的“構建基塊”以供設計師使用
確定其外殼零件的最佳材料和工藝。
There are cases where prototypes required for the final design need to be developed. These “prototypes” are certainly less cost-sensitive, as it is time that is usually the critical factor here. However, even though the prototype itself may not have a cost-sensitivity, the overall project cost is impacted in the sense that cost is sacrificed for speed just in the prototype portion of the project
在某些情況下，需要開發最終設計所需的原型。這些“原型”當然對成本不太敏感，因為時間通常是這裡的關鍵因素。然而，
即使原型本身可能不具有成本敏感性，但整個項目的成本
在某種意義上受到影響，因為僅在原型的一部分中就犧牲了速度成本
該項目
Time plays into this “cost picture” very much. The “time-to-market” can be a huge driver in product development. That is, if a certain product isn’t released in some specific time frame (such as the spring planting season or the electronic show before the holidays), that can mean a huge difference to the total sales of the product. So, coupled with cost is the aspect of time.
時間在這個“成本圖”中扮演了非常重要的角色。 “上市時間”可能是產品開發的巨大推動力。 也就是說，如果某個產品沒有在某個特定的時間範圍內發布（例如春季播種季節或節假日前的電子展覽），則可能對產品的總銷售額產生巨大的影響。 因此，成本是時間的一部分。
Emphasis on time in material/process/manufacturability choice for the early
stages of the development process
A “high-production” and cost-reduced product release can come occur in the
later stages of the development process
1.儘早選擇材料/工藝/可製造性
開發過程的各個階段
2.在產品中可能會出現“高產量”和降低成本的產品發布。
開發過程的後期
>>it could have been determined that the overall cost is minimized by a “two-stage”
可以確定通過上述“兩階段”將總成本降至最低
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Cost can also be broken down into several time frames, such as:
成本也可以細分為多個時間範圍，例如：
- Development cost (until first shipment to customer)
- Ongoing production cost of the product: materials/assembly/overhead
- Service and warranty costs after production
- End-of-life costs such as recycling
1.開發成本（直到首次交付給客戶）
2.產品的持續生產成本：材料/組裝/間接費用
3.生產後的服務和保修成本
4.報廢費用，例如回收利用
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Basic factors affecting costs:
影響成本的基本因素：
• Materials of the individual parts.
• Process needed to produce the above parts.
• Assembly procedure needed to assemble above parts.
• Testing procedure needed to test above parts and assemblies.
• Quality control procedures in place to assure parts and assemblies are produced
and assembled to specifications.
• Service (expected or unexpected) requirements are met.
•各個零件的材料。
•生產上述零件所需的過程。
•組裝上述零件所需的組裝程序。
•測試上述零件和組件所需的測試程序。
•制定質量控製程序以確保零件和組件的生產
並按照規格組裝。
•滿足服務（預期或意外）要求。
4.3 Materials and Process Choice(材料和工藝的選擇)
Once a designer has designed a part, the designer must determine the “best” Cost way for that part to be produced. The general items to be determined for each part are:
設計人員設計完零件後，必須確定要生產該零件的“最佳”成本方式。每個部分要確定的一般項目是：
• Material of the part.
• Finish required for the part (see next section).
• Dimensional accuracy needed for the part.
• Process by which that part will be produced (perhaps one process for early needs,prototyping, and preproduction of parts and a different process for mature production of the parts).
• Quantity needed of the part (say, per quarter, per month, per year).
• Second operations needed for the part (beyond finishing).
• Cost requirements for the part.
• Can this part be combined with another part in the design? Essentially, whatneeds to be determined is whether a single (combined) part can fulfill the functionality of the separate parts .
• Can the part be made symmetrical (for assembly ease)? Should the part that is almost symmetrical be made a more obvious
•零件的材料。
•零件需要的表面處理（請參閱下一節）。
•零件所需的尺寸精度。
•生產零件的過程（也許是用於早期需求，原型設計和零件預生產的過程，以及用於零件成熟生產的不同過程）。
•零件所需的數量（例如，每季度，每月，每年）。
•零件需要的第二次操作（超出精加工）。
•零件的成本要求。
•該部分可以與設計中的另一部分組合嗎？本質上，需要確定的是單個（組合）部分是否可以滿足單獨部分的功能。
•零件可以做成對稱的（為了便於組裝）嗎？應該把幾乎對稱的部分做成一個更明顯的非對稱部分嗎？這兩個問題涉及該零件的組裝以及以不正確的方式組裝的可能性。可以僅為使零件對稱而在零件上添加孔或缺口（多餘的）。
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Considerations for determining material selection for a part:
確定零件的材料選擇的注意事項：
The designer should choose a material that will satisfy (meet or exceed):
設計者應選擇滿足（超過）要求的材料：
- Strength requirements
- Weight requirements
- Reliability requirements
- Regulatory requirements
- Safety requirements
- Thermal requirements
- Shielding requirements (EMI/RFI)
- Compatibility requirements for metals (galvanic corrosion)
- Elastic requirements (durometer)
- Conductive (or insulating) requirements
- Opaqueness requirements
- Wear requirements
- Aesthetical requirements (touch, visual)
- Acoustical requirements
- Ultraviolet (UV) transmission and resistance requirements
1.強度要求
2.重量要求
3.可靠性要求
4.法規要求
5.安全要求
6.散熱要求
7.屏蔽要求（EMI / RFI）
8.金屬的兼容性要求（電腐蝕）
9.彈性要求（硬度計）
10.導電（或絕緣）要求
11.不透明要求
12.磨損要求
13.審美要求（觸覺，視覺）
14.聲學要求
4.7 Casting Metals(鑄造金屬)
There are actually quite a few processes for forming plastics, the same can be said for the casting process. There are many casting techniques. The casting techniques generally vary by:
實際上有很多塑料成型工藝，鑄造工藝也可以說相同。 有很多鑄造技術。 鑄造技術通常因以下因素而異：
• Metal cast
• Size range of part normally cast
• Tolerances expected to be held by process
• Cost of tooling
• Part price
• Surface finish expectation
• Minimum draft recommended
• Normal minimum section thickness
• Ordering quantity
• Normal lead time
• Die casting
• Permanent mold
• Investment (lost wax)
• Plaster mold
• Ceramic mold
• Graphite mold
• Resin shell mold
• Sand casting
•金屬鑄件
•正常鑄造零件的尺寸範圍
•公差應按工序確定
•工具成本
•單價
•表面光潔度期望
•建議的最低吃水深度
•正常最小截面厚度
•訂購數量
•正常的交貨時間
•壓鑄
•永久模具
•投資（失蠟）
•石膏模具
•陶瓷模具
•石墨模具
•樹脂殼模具
•砂模鑄造
4.8 Dimensioning/Tolerancing (尺寸/公差)
4.8.1 Choice of “Nominal Dimension” (“公稱尺寸”的選擇)
If this is not done correctly, the parts are in a rather constant state of “not fitting” and “out of tolerance,” and assembly line stop-page will occur. assembly and serviceability, as properly dimensioned and toleranced parts will lead to very smooth manufacturing assembly of those parts.Some comments about the English system of units vs. metric system of units are also appropriate (see separate discussion). I even want to start this discussion with how I actually started design “parts” (which were actually tooling fixtures and jigs to perform machining or welding of parts).
如果操作不正確，則零件處於“不適合”和“超出公差”的相當恆定的狀態，並且將發生裝配線停工。 裝配和可維修性，因為適當尺寸和公差的零件將導致這些零件的製造裝配非常順暢。關於英制單位制和公制單位制的一些評論也是適當的（請參閱單獨的討論）。 我什至要開始討論如何實際開始設計“零件”（實際上是工裝夾具和夾具）。
進行零件的機加工或焊接）。
4.8.2 United States Engineering Units Versus International System of Units (美國工程單位與國際單位制)
My comments about dimensioning/tolerances are useful in either system of units (inches or millimeters). In the United States, we may start a design thinking that 3.000 inches is nominal or “the place to start.” In Europe, the “same” place to start might be 75 millimeters (which is equal to 2.953 inches). If a design starts in the United States at 3.000 inches, those drawings are exactly converted to 3 × 25.4 = 76.2 millimeters if the product is to be manufactured in Europe. I’m trying to make a distinction between “conversion factor” (inches to millimeters) and “designer origin mindset.” So, if I was a designer in the United States (with a US education), who was designing a part for a European firm, I would probably create a design that had its start with an “even” millimeter nominal dimen-sion, so I would start with 75 millimeters as that size (instead of choosing 3.000 inch).
我對尺寸/公差的評論在單位制（英寸或毫米）中都非常有用。 在美國，我們可能開始設計時以3.000英寸為標稱尺寸或“起點”。 在歐洲，“相同”的起點可能是75毫米（等於2.953英寸）。 如果設計在美國以3000英寸開始，那麼如果要在歐洲製造產品，則將這些圖紙精確地轉換為3×25.4 = 76.2毫米。 我試圖在“轉換係數”（英寸到毫米）和“設計師出身的思維方式”之間進行區分。 因此，如果我是一位美國設計師（接受過美國教育），當時正在為一家歐洲公司設計零件，那麼我可能會創建一個以“甚至”毫米標稱尺寸開始的設計，因此 我將從75毫米開始（而不是選擇3.000英寸）。
4.8.4 Overall Size and the Design (總體尺寸和設計
為了繼續進行尺寸標註)
To continue the general topic of dimensioning and how it relates to design, Some constraints will usually be the start of a design. Here are some examples:
The general assumptions for the examples are:
為了繼續進行尺寸標註及其與設計的一般性主題，通常會遇到一些約束。
這裡有些例子：
這些示例的一般假設為：
The general assumptions for the examples are:
Minimum size and weight, Cost (Chpt4), are required in the design.
Minimum clearance between one object and another is 0.010 inch. This obviouslyvaries in a real design and depends on the objects and environment that the enclo-sure will be used.
設計中需要最小尺寸和重量，成本（Chpt4）。
一個物體與另一個物體之間的最小間隙為0.010英寸。 顯然，這在實際設計中會有所不同，並且取決於要使用外殼的對象和環境。
4.8.5 Theory of Tolerancing: The Need (4.8.5寬容理論：需要)
Tolerancing on part dimensions is needed as parts cannot be produced perfectly.
Manufacturing techniques do not produce perfect parts. This is probably obvious.
The actual amount of tolerance is based on a few (probably competing) factors:
由於零件無法完美生產，因此需要零件尺寸公差。
製造技術不能生產出完美的零件。這可能是顯而易見的。
實際的公差量基於幾個（可能是相互競爭的）因素：
- 成本（較大的公差製造成本較低）。
- 相似的零件（同一零件）需要互換-所有零件都是
公差必須起作用。
- 與其他零件配合的零件必須在所有零件都達到其公差極限的情況下執行此操作。因此，指定公差的“默認步驟”是：
A.Choose the tolerance for the reasonable or most common manufacturing process.
選擇合理或最常見的製造過程的公差。
B. If the above is acceptable to the design, look to increase the tolerance even more,checking back to acceptability in the overall design. Increasing the tolerance will
allow more parts to pass inspection, which should (could) result in overall cost reduction.
如果上述設計可接受，請尋求更大的公差，並重新檢查總體設計的可接受性。增加容忍度允許更多零件通過檢查，這將（可能）導致總體成本降低。
C. Tighten the tolerance even though the most common manufacturing process will not produce that tolerance if the design dictates that tighter tolerance. Check with the part manufacturer if that tighter tolerance will be achievable (reason-ably) or at what cost.Each dimension (location, hole size, angle, etc.) must have a tolerance, either explicitly stated on the drawing or as being a part of an overall notation on thedrawing.
收緊公差，即使最常見的製造工藝在設計要求更嚴格的公差的情況下也不會產生該公差。請與零件製造商聯繫，以確保（合理地）可以達到更嚴格的公差，或者以何種成本實現。每個尺寸（位置，孔的大小，角度等）都必須具有公差，公差可以在圖紙上明確說明，也可以作為圖紙上整體符號的一部分。
4.8.7 Inspection Dimensions (Critical Dimensions) (檢驗尺寸（關鍵尺寸）)
Parts can have hundreds of dimensions. To fully specify every feature on some parts takes a fair amount of time. Historically, every feature on a drawing was dimen-sioned to enable that feature to be inspected and found either in compliance with the specification (drawing) or non-compliant. With the advent of 3D CAD systems for
designing and creating drawing documentation, it is completely possible to transfer all of the part information digitally, without any dimensions being specified actually on the drawing, and have that part manufactured at the “nominal specified dimen-sion.” That is, features that are 3.000 inches apart are “drawn” exactly 3.000 inches
apart, and that number is an integral part of a file that the part manufacturer gets.Anyone who brings up that part file on their CAD system can query that file and see those features need to be 3.000 inches apart (with a stated tolerance as a part of the CAD file). In fact, inspection departments, if they had access to the CAD file, could inspect the part
零件可以具有數百個尺寸。要完全指定某些零件上的每個功能需要花費大量時間。從歷史上看，對圖紙上的每個特徵都進行了尺寸標註，以便可以檢查和發現該特徵是否符合規範（圖紙）或不符合規範。隨著3D CAD系統的出現
設計和創建工程圖文檔時，完全有可能以數字方式傳輸所有零件信息，而無需在工程圖上實際指定任何尺寸，而使零件以“標稱指定尺寸”進行製造。也就是說，相隔3.000英寸的要素將精確地“繪製” 3.000英寸
零件號是零件製造商獲取的文件的組成部分。在其CAD系統上顯示該零件文件的任何人都可以查詢該文件，並看到這些特徵需要相距3.000英寸（以規定的公差作為單位）。 CAD文件的一部分）。實際上，檢查部門如果可以訪問CAD文件，則可以檢查零件
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