Free-Cutting Brass for Lower Screw Machine Product Cost: Pneumatic Hose Fitting / Temperature Sensor

PNEUMATIC HOSE FITTING APPLICATION

APPLICATION Aircraft
SPECIAL FEATURES Costly Deep-Hole Drilling
PART WEIGHT 0.059 pounds (Brass)
BRASS RAW MATERIAL PREMIUM 42% (Including Turnings Allowance)
CYCLE TIME (C360 BRASS) 3.7 sec (781 pieces/hr @ 80% Efficiency)
CYCLE TIME (LEADED STEEL) 8.3 sec (304 pieces/hr @ 70% Efficiency)
PRODUCTIVITY GAIN USING BRASS 157%
NET COST SAVINGS (BRASS VS. BARE STEEL) 22%, $35.17 per 1000
NET COST SAVINGS (BRASS VS.PLATED STEEL)* 26%, $43.90 per 1000
* Zinc/chromate; assumes 0% plating rejects.

Leaded Steel Part Now Free-Cutting Brass

This pneumatic hose fitting is a precision product designed for airline service. Now made from Free-Cutting Brass, Copper Alloy 360 (UNS C36000), the fitting takes less than four seconds to machine on an Acme-Gridley RA6. Its deep axial hole could make the part difficult and expensive to produce. In fact when this fitting was formerly made from 12Ll4 leaded steel it took more than twice as long to machine and cost 22% more than it now does in brass.

Automatic screw machine parts often cost less in brass than steel. Why? One reason is that typical screw machine parts require a lot of machining-for this pneumatic fitting, about 66% of the starting stock ends up as turnings. These brass turnings have a high recycle value, which is always credited against the raw material cost by the screw machine house. But the main reason brass parts cost less is that Free-Cutting Brass machines so much faster than leaded steel; the better machinability of brass resulted in a 157% productivity gain for the fitting shown above. Remember, when you're buying screw machine parts you're really paying for machine time. The faster the cut, the lower the cost.

BRASS IS AS STRONG AS STEEL

Many designers don't realize that the strength of half-hard Free-Cutting Brass and cold-reduced 12Ll4 leaded steel (the most common conditions for screw machine parts) overlap the same range. Here are the published nominal values:

MATERIALTENSILE PROPERTIES
YIELD STRENGTHULTIMATE STRENGTH
C36000 45 ksi 58 ksi
Hot Rolled 12L14 34 ksi 57 ksi
Cold Drawn 12L14 60 ksi 78 ksi

That means that for almost one-half of all screw machine products, brass can be substituted for leaded steel without any sacrifice in strength or safety.

ELIMINATE PLATING COSTS

Ordinary zinc/chromate plating typically adds between 11 and 16 cents per pound to the cost of steel screw machine products. And it's difficult to insure uniformity when plating threads, sharp corners or deep holes. Now that this pneumatic hose fitting is made from Free-Cutting Brass, it doesn't have to be plated. Brass's natural corrosion resistance uniformly protects the entire surface. Strength, economy, corrosion resistance... BRASS means quality.

TEMPERATURE SENSOR

APPLICATION Automotive
SPECIAL FEATURES Deep Blind Hole,
PART WEIGHT 0.032 lb. (Brass)
BRASS RAW MATERIAL PREMIUM 32% (Including Turnings Allowance)
CYCLETIME (C360 BRASS) 4.8 sec (565 pieces per hour @ 80% Efficiency)
CYCLETIME (12L14 STEEL) 8.1 sec (327 pieces per hour @ 70% Efficiency)
PRODUCTIVITY GAIN USING BRASS 73%
NET COST SAVINGS (BRASS VS. BARE STEEL) 17% = $39.00 per 1000
NET COST SAVINGS (BRASS VS.PLATED STEEL) * 21% = $48.18 per 1000
*Zinc/chromate; assumes 0% plating rejects.

STRENGTH PLUS CORROSION RESISTANCE EQUALS SAFETY

This temperature sensor, a typical screw machine part, must provide strength and corrosion resistance to satisfy automotive requirements. It was originally made from 12L14 leaded steel and zinc/chromate plated, to retard corrosion from water and road salts. The sensor is now produced in Free-Cutting Brass, Copper Alloy 360 (UNS C36000) and it's as strong as steel but doesn't have to be plated… so it costs 21% less. The strength of half-hard Free-Cutting Brass is in the same range as 12L14 steel. Published nominal values for these materials are:

MATERIALTENSILE PROPERTIES
YIELD STRENGTHULTIMATE STRENGTH
C36000 45 ksi 58 ksi
Hot Rolled 12L14 34 ksi 57 ksi
Cold Drawn 12L14 60 ksi 78 ksi

That means that for almost one-half of all screw machine products, brass can be substituted for leaded steel without any sacrifice in strength or safety.

BRASS PARTS COST LESS THAN STEEL

Many designers think that because brass costs more than steel, machined brass parts must cost more too. That's not true for typical screw machine jobs. Only brass rod's off-the-shelf material cost is significantly higher; this sensor produces more than three times as much turnings weight as it does product and after discounting for the turnings' high value, the net material cost difference is only 32%.

HIGH MACHINABILITY MEANS LOWER PRODUCTION COSTS

When you buy machine parts you are paying for machine time. The faster the cut, the lower the cost, and free cutting brass machines faster than leaded steel. The productivity gained by switching from steel to brass for this actuating sleeve was a very significant 73%.

ELIMINATE PLATING COSTS

Steel rusts, brass tarnishes; an important difference. Exposed steel screw machine parts must be zinc/ chromate plated. Brass parts are ready to use without protective platings. The savings are between 11 and 16 cents per pound of product. If your part has deep holes, threads, or sharp corners, it can be difficult to insure uniform plating on all surfaces. Make the part in brass in you eliminate that concern. The natural corrosion resistance of brass uniformly protects the entire surface. If decorative plating is desired, brass plates more easily and is better looking than plated steel.