Suitable aluminum alloys...

[Stuka]

Anyone here willing to provide a brief lesson on aluminum alloys and their suitability for our projectors?

I found a local vendor that can provide "3003 H14 Mill Finish" 1/4" aluminum plates cut to order, and was wondering about the suitability of that particular alloy & finish for use as optical base plates.

Thanks!

[frothychimp]

Should be fine. It's a manganese doped alloy so it's stronger than pure aluminum plate. I just wouldn't be torquing bolts to tightly (which you should not be doing in a projector anyway).

If you plan on anodizing it you might consider 6063 as an option.

EDIT: Here I found this info. Should help:

1100 This grade is commercially pure aluminum. It is soft and ductile and has excellent workability. It is ideal for applications involving intricate forming because it work hardens more slowly than other alloys. It is the most weldable of aluminum alloys, by any method. It is non heat-treatable. It has excellent resistance to corrosion and is widely used in the chemical and food processing industries. It responds well to decorative finishes which make it suitable for giftware.
2011 This is the most free-machining of the common aluminum alloys. It also has excellent mechanical properties. Thus, it is widely used for automatic screw machine products in parts requiring extensive machining.
2014 & 2017 The 2017 alloy combines excellent machinability and high strength with the result that it is one of the most widely used alloys for automatic screw machine work. It is a tough, ductile alloy suitable for heavy-duty structural parts. Its strength is slightly less than that of 2014.
2024 This is one of the best known of the high strength aluminum alloys. With its high strength and excellent fatigue resistance, it is used to advantage on structures and parts where good strength-to-weight ratio is desired. It is readily machined to a high finish. It is readily formed in the annealed condition and may be subsequently heat treated. Arc or gas welding is generally not recommended, although this alloy may be spot, seam or flash welded. Since corrosion resistance is relatively low, 2024 is commonly used with an anodized finish or in clad form (“Alclad”) with a thin surface layer of high purity aluminum. Applications: aircraft structural components, aircraft fittings, hardware, truck wheels and parts for the transportation industry.
3003 This is the most widely used of all aluminum alloys. It is essentially commercially pure aluminum with the addition of manganese which increases the strength some 20% over the 1100 grade. Thus, it has all the excellent characteristics of 1100 with higher strength. It has excellent corrosion resistance. It has excellent workability and it may be deep drawn or spun, welded or brazed. It is non heat treatable. Applications: cooking utensils, decorative trim, awnings, siding, storage tanks, chemical equipment.
5005 This alloy is generally considered to be an improved version of 3003. It has the same general mechanical properties as 3003 but appears to stand up better in actual service. It is readily workable. It can be deep drawn or spun, welded or brazed. It has excellent corrosion resistance. It is non heat-treatable. It is well suited for anodizing and has less tendency to streak or discolor. Applications same as 3003.
5052 This is the highest strength alloy of the more common non heat-treatable grades. Fatigue strength is higher than most aluminum alloys.In addition this grade has particularly good resistance to marine atmosphere and salt water corrosion. It has excellent workability. It may be drawn or formed into intricate shapes and its slightly greater strength in the annealed condition minimizes tearing that occurs in 1100 and 3003. Applications: Used in a wide variety of applications from aircraft components to home appliances, marine and transportation industry parts, heavy duty cooking utensils and equipment for bulk processing of food.
5083 & 5086 For many years there has been a need for aluminum sheet and plate alloys that would offer, for high strength welded applications, several distinct benefits over such alloys as 5052 and 6061. Some of the benefits fabricators have been seeking are greater design efficiency, better welding characteristics, good forming properties, excellent resistance to corrosion and the same economy as in other non heat-treatable alloys. Metallurgical research has developed 5083 and 5086 as superior weldable alloys which fill these needs. Both alloys have virtually the same characteristics with 5083 having slightly higher mechanical properties due to the increased manganese content over 5086. Applications: unfired pressure vessels, missile containers, heavy-duty truck and trailer assemblies, boat hulls and superstructures.
6061 This is the least expensive and most versatile of the heat-treatable aluminum alloys. It has most of the good qualities of aluminum. It offers a range of good mechanical properties and good corrosion resistance. It can be fabricated by most of the commonly used techniques. In the annealed condition it has good workability. In the T4 condition fairly severe forming operations may be accomplished. The full T6 properties may be obtained by artificial aging. It is welded by all methods and can be furnace brazed. It is available in the clad form (“Alclad”) with a thin surface layer of high purity aluminum to improve both appearance and corrosion resistance. Applications: This grade is used for a wide variety of products and applications from truck bodies and frames to screw machine parts and structural components. 6061 is used where appearance and better corrosion resistance with good strength are required.
6063 This grade is commonly referred to as the architectural alloy. It was developed as an extrusion alloy with relatively high tensile properties, excellent finishing characteristics and a high degree of resistance to corrosion. This alloy is most often found in various interior and exterior architectural applications, such as windows, doors, store fronts and assorted trim items. It is the alloy best suited for anodizing applications - either plain or in a variety of colors.
7075 This is one of the highest strength aluminum alloys available. Its strength-to weight ratio is excellent and it is ideally used for highly stressed parts. It may be formed in the annealed condition and subsequently heat treated. Spot or flash welding can be used, although arc and gas welding are not recommended. It is available in the clad (“Alclad”) form to improve the corrosion resistance with the over-all high strength being only moderately affected. Applications: Used where highest strength is needed.

[Doc]

Nice little reference that, should be a sticky

[Laser Ben]

Here is what I have to say about what I have used milling.

2024: A nightmare, it's hard on tools and to get a decent cut, you need to use carbide.

3003: Sticky, horrible, crappy, useless! A lot like copper. Don't work with it if you can help it. If you do have to, use a sharp HSS tool with a good coating!

6061: Awesome! Machines easily and has no issues with chip cloging/sticking. Use any decently sharp tool on it.

7075: Pretty similar to 6061, but you need to go slower and/or take lighter cuts.

[frothychimp]

From the post I get the impression he wont be machining them.

[danielbriggs]

3003 doesn't anodise well at all, and is only ok for machining, not great.
If you can, get 6082 or 6061 they are the most suitable in this case; they machine well, anodise very well and can be heat treated (but usually come pre heat treated) T6 is the top. 6082 starts from around 6mm upwards.
If you can't get 6082 or 6061, try and go for 5083. (5083 goes up to about 1/2" plate. ) If you can't get either of these, then 3003 will have to do. Do NOT get the sheets cut to size on a guillotine.
Keep well away from 7000 series alloys if you ever plan to anodise; it can be done, but is a hell of a lot more complicated / expensive.

Hope that helps,
Dan

Edit: Spot on Ben. Try and get the sheets cut with a bandsaw. NOT A GUILLOTINE,
Also, mill finish means the finish produced from the rolling process, picks up fingerprint marks very well due to the thin oxide layer

[Stuka]

Thanks to all who chimed in!

Hopefully, the only machining I'll need to do is drill & tap a few holes - that's why I'm looking for the "cut to size" purchase option!

[danielbriggs]

If you're drilling lots of holes, don't systematically drill them row by row. The metal will warp, you need to relieve the stresses evenly, as the metal has been rolled.

[MechEng3]

Let me know what you want...and sizes......may be able to help. I have a couple of places I work at most of the time that stock 6061 and some 7000 series...even inconel...not that you will need any. I do have an ongoing titanium collection. Lots of odds and ends...mostly from a local aircraft seating manu. It wil machine very well with ceamic inserts.The Furchas corp. has several CO2 cutting CNC machines and a HUGE shear.

[300EVIL]

6061 is great for baseplates. That's what I use.