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All About Surface Finishes

Friday, 15 June 2018 00:00:00

When it comes to die casting, most parts utilize some sort of finish

Now that you have your casting design, you’re starting to think about surface finishes options. If you don’t know what questions to ask, choosing a surface finish or plating could get tricky. We have compiled a run-through of factors to take into consideration when selecting a surface finish as well as different surface finish characteristics.

Do I need a surface finish?

While most castings do require a surface finish, it is not always necessary.

There have been advancements in alloys that have allowed us to provide raw castings where a finish would normally have been required. For instance, when casting an aluminum 380 alloy, traditionally you would normally have wanted a chem film or anodizing for corrosion resistance. With the advent of K-Alloy, we’ve been able to provide parts without an additional finish that meet or exceed the requirements of the customer’s original intent, therefore saving them a lot of money. There have been advancements in zinc alloys as well.

While these advancements have greatly improved our casting processes, they’re not necessarily applicable to each particular application. We suggest talking with your die cast manufacturer or asking an engineer for more information on raw castings.

Discovery phase

After you have decided that your part does need a surface finish, it is important to walk through what we call the “discovery phase.” Here we highlight important aspects that you need to consider in terms of your part design, the functionality of the part, and some price considerations. These are some useful questions to ask yourself when narrowing down your finish options:

Do I need a decorative finish?
Do I need enhanced corrosion protection?
Do I need enhanced wear properties on the substrate?
Do I need a 100% leak-proof casting?

Die casting process control

After you’ve spoken with your design and engineering team to determine what surface finish is best for your project, your next consideration is process control. In many cases, the performance of your chosen finish is dependent on the quality of the substrate or the casting. Over the years, we have found that there are key process parameters that need to be monitored during the die cast process. When choosing a die casting company, you need to have a conversation about how they plan on monitoring process parameters. If you have control of your process and you’re monitoring it appropriately, you’re manufacturing quality into the component.

It is important to note that the process is more than just die casting. The process begins with a tool design based on the part manufacturability and tool construction. Because of this, you want to get your die caster involved as early as possible so that the part is designed with things like mold flow analysis and construction in mind.

For more details on surface finish prep, including surface cleanliness, deburring, vibratory shot blasting, download our full on-demand seminar.

Popular die casting surface finishes

While there are many different surface finishes available and more that are invented daily, we cover the most popular surface finishes and some notable takeaways below:

Anodizing: Non-conductive protective coating that seals the part. Comes in a variety of colors including red, blue and black. This is a very affordable option to create durability and corrosion resistance.

Chromate: Cost-effective bulk process conversion coasting. Typical salt spray hours are 150 hours per trivalent chrome but you can increase that considerably with sealers. This coating also comes in a variety of different colors.

E-Coat: Racked process, adding more cost in the racking and un-racking process. You get really great coverage with e-coat. It is often used on its own but can also be used as an undercoat for subsequent coatings like a powder coat. Traditionally more functional than decorative, though Dynacast has been successful in providing decorative components using e-coat.

Black Oxide: Primarily used on ferrous metals—also copper. You see this a lot on firearms because of its uniform black finish. There is no dimensional change with this coating and it is resistant to peeling and chipping. It provides some corrosion resistance and acts as an excellent vehicle to absorb oils and waxes.

Powder Coat: One of the most popular finishes. It’s cured at higher temperatures so it is a tougher finish. Generally, scratch and ding resistant. Available in different colors, gloss levels, and textures. Given that is it cured at higher temperatures, it is important to have a very controlled die casting process.

Chrome Plated: One of the more expensive finishes due to the amount of labor involved in chrome plating. Provides a mirror-like finish. There is bright chrome that is used quite a bit in the automotive industry. As well as satin chrome that creates a pearlescent look. 1,000+ salt spray hours so it is great for exterior parts.

Bright Nickel: Applied over copper and under chrome for a decorative finish. It is a fairly brittle plating so if you have a part that may be bent or crimped after plating this would not be something you’d want to consider.

Chem Film: Used on aluminum die castings. It differs from anodizing in that is electrically conducted. It is a conversion finish, so there’s really no plating buildup. You can apply it either by a dipped process, spray, or even brush—dip being the most common.

Copper-nickel-tin: Utilized to provide solderability to the base metal substrate. There is a matte tin that generally has better solderability, but bright tin is specified more because of its appearance.

Cobalt tin: Not quite as expensive as chrome finishes, but it is a racked process. Instead of getting the copper-nickel-chrome, it is a bright nickel with a flash of cobalt-tin. It actually looks similar to bright chrome, but it’s less expensive and it has very good corrosion resistance and wear properties.

Electroless nickel: Unique in that the nickel is not applied via electrolysis, it’s submerged in a bath. Provides very uniform plating thickness. There’s low-phos, mid-phos, high-phos. Phos pertaining to the amount of phosphorus content in the bath. So the lower phosphate content leads to higher density nickel. The low-phos, you’re going to have excellent wear properties, but the finish is going to be brittle. Then high-phos is going to be more ductile.

Gold plating: Doesn’t oxidize and it retains its connectivity and solderability at normal temperatures. Used primarily in the electronics industry for connectors, printed circuits, transistors, and integrated circuits—anywhere where contact resistance, solderability, or wire bonding is crucial. The excellent physical and chemical properties of it can offset the whole price of the gold. More expensive, but depending on the application it’s money well spent.

Silver: Low cost but it’s susceptible to tarnish when exposed to the atmosphere. It is somewhat of a decorative finish but it has the highest electrical and thermal connectivity of any metal, so it’s highly ductile, malleable, and solderable.

Nickel-Free Coating: Hypoallergenic finish. Great for consumer electronics and wearables. We have a whole blog post on nickel-free coatings.

Polyurethane paint: Long lasting and intended for exterior use. It is a little thicker so you’ll want to keep in mind what it mates to. Wet process and water-borne paints, in general, are very durable once they’ve cured.

Impregnation: Seals porosity, creating watertight components. Very viable option to improve your yields and reduce your scrap. Also, a great option to use after machining when you remove the “skin” of the casting to create a leak-free component.

Teflon: Thermally cured solid film lubricant. Excellent corrosion resistance. Utilizes a rack process.

If you’d like a more in-depth overview of our surface finishes, visit our full library of surface finish and plating options—filter by benefit to see what options are available for your project needs.

Register below for access to the full on-demand webinar, Surface Finish 101.

薄壁鋁合金壓鑄

Tuesday, 11 April 2017 12:00:00

想到鋁壓鑄時，您是否想到的是大而笨重，剖面極厚的零件？沒關係，我們以前也是如此！如果我告訴你，我們現在可以鑄造重量幾乎與鎂合金一樣輕的鋁合金零件，並提供更多優點，如更強的抗拉強度還有額外的加工整理選擇呢？過去，設計工程師總是會避開鋁壓鑄件，因為鋁壓鑄件需要較厚的鑄壁（傳統是1.5mm – 2.0mm），因此產生較重的零件。

您可能會問：「為什麼鑄造薄壁鋁有其困難？」那是因為鋁的熔點與凝固點都很高，因此，當熔融金屬注入模具時，鋁會開始快速冷卻成為固體狀。在液態到固態之間的時窗非常窄，這表示要製作薄壁功能的零件，充填時間必須低於30毫秒。我們的工程師以極為精確的製程控制來達到這個目標，即使是十幾個變項的微小調整都是成與敗的關鍵因素。優異的模具設計也同樣重要。我們的模具工程師必須找出流道系統與澆注設計、正確的溢流放置與設計、以及標的性熱管理之間的完美平衡。

對鋁合金沒有興趣？快來試試我們的動態金屬選取器，比較其他合金的機械與物理特性。

薄壁鋁合金技術的發展

以往，為了鑄造具薄壁剖面的鋁合金，必須使用特製的高流動性合金。但是，我們的工程師最近開發出一種將此技術應用到標準合金的方法。利用改良後的製程控制，先進的模具設計以及強化機器功能，我們徹底的從根本上改造了壓鑄業。

薄壁鋁壓鑄的優點

薄壁鋁合金壓鑄 | Dynacast | 壓鑄公司薄壁鋁合金壓鑄最重要的一個優點是能製造更輕量的零件—並且，比起其他壓鑄合金，薄壁鋁合金壓鑄還有更多表面加工處理的選擇。製造壁厚0.5mm的零件取代壁厚2mm的零件，等於減少75%的重量，這可說是了不起的一大進步；對於想減輕重量的汽車零件與手持行動裝置的業者來說，更是大好的消息。鋁合金也是能夠承受所有壓鑄合金的最高工作溫度。還有，壓鑄鋁具備多種用途並且耐腐蝕；即使鑄壁薄也保有很高的尺寸安定性，並且幾乎可以使用於任何產業中。

如果您想進一步瞭解我們的薄壁鋁壓鑄製程，請立即聯絡我們的團隊！我們很願意與您一起審視您的專案並提供報價。

多軸式與傳統式壓鑄的比較

Monday, 01 August 2016 12:00:00

我們的多軸式壓鑄製程最早於1936年開發出來。從當時至今，我們仍然在模具與機器上持續改良。如果您仍然在使用傳統式壓鑄製程，花點時間瞭解多軸式製程的原理是很值得的事，您可能會發現它更適合您的計畫。如果您的零件重量不到400克，選擇多軸式製程通常更為合適。較大零件非常適合利用傳統式壓鑄來製造，但我們的A2或A3機器並不適合生產這類零件。傳統式壓鑄與多軸式壓鑄，兩者間最大的差異在於模具的結構與操作，以及用來操作模具的機器類型。

Dynacast模具

傳統式壓鑄使用的是以兩個部件組成的模具，而多軸式壓鑄則使用至少4個垂直滑塊。在生產結構複雜的小型零件時，使用較多模塊就能減少誤差並能節省成本。每一個模塊表面都有一個穴或心型。組合一起後，熔融金屬被注入模穴，零件即開始鑄造。

我們的工程師與設計師始終在零件設計的領域裡追求極限，希望設計出更小更複雜卻有多功能的零件；如果您的零件重量是在400克以內，我們的多軸式壓鑄製程是您最佳的選擇。我們一樣能使用我們的傳統式壓鑄機製造精密零件；但是，如果要求的是一致性與準確性，那麼多軸式壓鑄模具就是不二之選。

不論製程為何，我們始終將重心放在模具的設計上，儘可能將需要的零件功能放入其中以避免二次加工。我們的目標就是要在第一次，而且是每一次就要達到精準成形。如此仔細的規畫即能避免機械加工，並降低整體零件成本。

為確保模具的使用壽命，我們的模具設計師會預測模具中的哪一部份容易磨損，然後將其設計成模具裡獨立的一個單位，如此一來，出現磨損時，我們即可輕易的更換這獨立的部位而不必更換整套模具。這種做法，不僅可以節省客戶可觀的費用，還能確保我們以客戶的計畫為基礎快速執行製造，無需重新製造一套完整的模具。

專利壓鑄機

我們特有的多軸式壓鑄機只在Dynacast使用。目前我們的多軸式壓鑄機再升級，配備了多個推進器，這是一套靈活的十字頭配接系統，也是一套快速氣壓系統。我們能快速的充填機器而不帶毛邊，如此能改善零件的表面品質，減少零件孔隙。多軸式壓鑄機讓我們能夠大量生產零件之餘，仍能確保最佳品質。

隨著時間過去，機台年齡、零件磨損、技術等都可能會過時。我們所有的機器都在廠內自行製造，因此，我們的專業團隊能持續將我們的多軸式與傳統式壓鑄機，以及其控制器進行升級與改良。

多軸式壓鑄

我們的多軸式製程是小而複雜的零件的最佳選擇。我們能製造精準成形的零件，特點是無需二次加工，包括內部與外部螺紋處理。我們始終運用最新且優化的模具與機器，為客戶提供最佳品質的零件。欲進一步瞭解我們的專利多軸式壓鑄製程或要求報價，請馬上聯絡我們的工程師。

壓鑄件的設計技巧

Wednesday, 31 December 1969 00:00:00

公差

Friday, 19 April 2024 22:40:32

設定公差標準

對於公差我們有不同的看法。我們的標準符合並超越業界標準，並且已成為全球設計人員的指標。我們相信嚴格的公差有其必要性而非可能性。

我們也相信，公差的嚴格程度以及能夠達到的製程能力並不是最重要的。相反的，我們視需要來滿足功能性的要求，而尺寸與部位才是重要關鍵。然後，我們選擇能夠達成這些尺寸與部位需求的製程。

我們看待公差時會審慎評估：

零件的形狀
模具內接近的部位
與零件上其它部位的關係

我們永遠會考慮模具壽命與損耗，因為這會影響短期與長期的製程能力。

移動模

線性尺寸

分割線

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