Metal and surface-treatment comparisons
How do aluminum 6061, 6063 and 7075 differ?
6061 is a versatile, machinable structural aluminum with good strength and corrosion resistance. 6063 is commonly selected for extruded profiles and attractive anodized appearance but is generally less strong. 7075 offers much higher strength but costs more and is less corrosion resistant than 6061. Availability and stock shape also affect price and lead time.
What is the difference between stainless steel 303 and 304?
303 contains additives that improve machinability, often reducing cutting time and cost. 304 provides better general corrosion resistance and weldability but is more difficult to machine. Choose 303 for machinability when the environment permits, and 304 where corrosion performance or welding matters more.
When should carbon steel or tool steel be used?
Carbon steel is economical and strong but normally needs coating or oil protection against rust. Tool steels are selected for wear resistance, hardness and tooling applications; they may require heat treatment and grinding or EDM. Heat treatment adds lead time and can create dimensional movement that must be planned.
How do brass and copper differ for CNC parts?
Brass machines easily, has a gold-colored appearance and provides useful corrosion resistance, so it suits fittings and decorative or electrical parts. Copper offers excellent electrical and thermal conductivity but is softer and can be more challenging to machine cleanly. Copper material and machining cost are usually higher.
When is titanium worth the higher cost?
Titanium is useful when high strength-to-weight ratio, corrosion resistance or biocompatibility justifies its material and machining expense. It cuts slowly, retains heat at the tool and often requires careful process control. Aluminum or stainless steel is usually more economical when titanium's specific properties are not essential.
What does an as-machined finish look like?
An as-machined part retains fine tool marks from cutting. It is the fastest and lowest-cost finish because no separate cosmetic treatment is added. Appearance varies with geometry, tool path, material and required roughness, so it should not be assumed to be perfectly uniform or mirror-like.
What is bead blasting and how does it affect appearance?
Bead blasting creates a uniform matte or satin texture by propelling fine media at the surface. It reduces visible machining marks but can soften sharp edges and does not by itself provide strong corrosion protection. It adds modest cost and usually some processing time.
What is the difference between Type II and hard anodizing?
Conventional Type II anodizing gives aluminum corrosion resistance and decorative color with a relatively thin oxide layer. Hard anodizing produces a thicker, harder, more wear-resistant layer and is normally more expensive. Both can alter dimensions, so tight fits and threaded features may need masking or allowance.
How do anodizing colors affect consistency and lead time?
Black and clear are commonly available and often easier to schedule. Custom colors may need minimum batch quantities, color samples and extra processing time. Shade can vary with alloy, surface texture, part geometry and batch, so exact color matching should be agreed before production.
How do powder coating and wet painting compare?
Powder coating creates a durable, relatively thick coating in many colors and is good for external parts. Wet paint can provide broader color and gloss options or thinner coverage but may be less wear resistant. Both require surface preparation, curing or drying, masking and extra lead time.
What are electroplating and electroless nickel plating?
Electroplating deposits metal using electric current and includes zinc, nickel, chrome and other coatings. Electroless nickel uses a chemical process and often gives more uniform coverage on complex geometry. Plating improves appearance, corrosion or wear performance but adds thickness, cost and usually several working days.
What are passivation, black oxide and zinc plating used for?
Passivation improves the corrosion behavior of stainless steel without adding a decorative coating. Black oxide gives steel a dark appearance with limited corrosion protection and usually needs oil or wax. Zinc plating gives carbon steel more practical corrosion protection and can have clear, blue or yellow appearances.
Which finish is best for a low-cost cosmetic prototype?
As-machined is cheapest but shows tool paths. Bead blasting creates a more even matte appearance at modest added cost. For aluminum, bead blast plus black or clear anodizing is a common premium-looking option, but it adds outsourced processing time. The right choice depends on how closely the prototype must represent production.
How much time should surface finishing add?
Simple in-house deburring may add little time. Outsourced blasting, anodizing, plating, heat treatment, coating or custom color commonly adds several working days and sometimes longer for special batches. The quotation should identify machining and finishing lead times together.