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QD SERIES


DUAL CHAMBER OVER/UNDER HEAT TREATING FURNACES 2350¡F / 1250¡F (1285¡C / 675¡C)

The QD Series Dual Chamber Heat Treating furnaces feature a 2350°F (1285°C) high heat chamber for hardening and a 1250°F (675°C) recirculating oven for tempering. The over/under configuration saves floor space. The hardening furnace is mounted on top with the tempering oven below. Agitated and heated quench tanks are optional. The furnaces achieve high precision by featuring highly accurate controls, mercury contactors for fast cycle times, two zone control (top and bottom) on the hardening furnace, and very even spacing of elements. The tempering oven features a powerful fan and recirculation muffle for high uniformity.

FEATURES

HIGH TEMPERATURE UNIFORMITY
The hardening furnace is uniform to within +/-20F (+/-10C) above 1500F (815C). The tempering oven is uniform to within +/-10F (+/-5C) above 300F (150C).

TWO ZONES AND EVEN ELEMENT PLACEMENT
The elements of the each furnace are divided into top and bottom zones. The control output is routed through two input switches which allow adjustment of the total time on to each zone. There are thermocouples mounted in the top and bottom with a selector switch to read the temperature differential. The elements of the hardening furnace are evenly spaced on the door, back, sides and bottom. The tempering furnace has no door or back elements. The elements are supported in proprietary high temperature ceramic element holders. These provide perfect support for the coiled element as well as excellent radiating characteristics. The smooth surface prevents premature failure of the element as it expands and contracts. Iron-aluminum-chrome alloy elements are standard although nickel-chrome elements are optional.

EFFICIENT MULTILAYERED INSULATION
Both chambers are insulated with 4-1/2” of low K factor refractory firebrick as the primary insulation. This is backed up by 2” of very low K factor mineral wool board on all surfaces except the bottom which has 2” of hard calcium silicate back up for so lid hearth support. This yields an excellent combination of strength, insulating quality and fast heat up and cool down time. All refractory is coated with a special facing that prolongs firebrick life and helps prevent spalling and dusting. The refractory sections are available completely shaped for easy replacement without cementing. All sections fit together with engineered heat locks which improve the insulating integrity of the furnace. No asbestos is used.

HEAVY DUTY INTEGRATED CASE
Both chambers are mounted in one integrated 10 gauge steel case with structural stiffeners and lifting rings. The entire case is primed with 800F silicone paint and finished in machine enamel.

FAN AND RECIRCULATION MUFFLE
The tempering oven features a back mounted four bladed alloy fan. It is belt driven with a 3/4 H.P. motor. A heat dissipator protects the bearings. The removable recirculation muffle is constructed of 304 stainless steel. This has a solid bottom for use as the hearth. The muffle protects the work from direct radiation of the elements and creates a recirculation pattern for the air.

HARDENING FURNACE FEATURES CERAMIC HEARTH
The standard hearth is a 3/4” thick ceramic plate elevated 1-1/2” above the bottom elements.

DOUBLE PIVOTED PLUG DOORS
Both doors are double pivoted horizontal doors with 1/2” refractory plugs for a superb heat lock around the door seal. The double pivoting allows the door to be opened so that the hot face stays away from the operator.

DIGITAL PID CONTROL AND HIGH LIMIT SYSTEM
The standard controls are Honeywell UDC 2300 digital PID 3 mode tuning controls. All fuses, transformers, contactors, and controls are housed in a NEMA 1 panel. Quiet, long life mercury power contactors are standard. SCR power controls are optional. The thermocouples are Type K. Thermocouple break protection is included. Limit switches shut off furnace power when doors are opened or the backs are removed. Lighted NEMA 13 On/Off switch included. Control voltage is transformed to 120 volts. A Honeywell UDC 2300 digital high limit back up control with manual reset, back up contactors and separate thermocouple is standard for both chambers. The control circuit and each power branch circuit are fully fused. Customer must connect fused power supply to single point on panel.

TESTING AND INSTRUCTIONS
The furnace is power tested to insure proper watt ratings. A complete instruction manual includes easy start up instructions, theory of operation, maintenance instructions, parts list, and a detailed trouble shooting guide. A ladder logic diagram and panel layout are prepared on CAD for easy readability.

WARRANTY
The furnace is warranted for one year except for elements and thermocouples (warranted for 6 months.)


OPTIONS


  • JIC CONTROL OPTION: This includes a NEMA 12 control cabinet, all oil tight switches and a panel mounted fused disconnect switch. Zone switches are percentage timers.
  • HIGH K.W.: Available on hardening furnace.
  • SCR POWER CONTROL: For greater precision.
  • INERT ATMOSPHERE CONTROL: Available on one or both chambers. Mixing panels for natural gas and nitrogen are available for neutral hardening.
  • CONTROL, RECORDER AND ELECTRICAL OPTIONS
  • VERTICAL DOORS: Counterbalanced vertical door is available for the hardening chamber only. Manual hand crank, pneumatic or electric operation.
  • SPECIAL HEARTHS: Silicon Carbide or alloy hearth.
  • AGITATED, HEATED QUENCH TANKS: These provide superior quenching results.
  • See OPTIONS Page

SPECIFICATIONS

MODEL NO
ACTUAL HARD CHAMBER
UNIFORM HARD CHAMBER
INSIDE RECIRC TEMP CHAMBER
OUTSIDE DIMENSIONS
HARD
TEMP
MAX LOAD WGHT
APPRX SHIP WGHT
 
IW
IH
ID
W
H
D
IW
IH
ID
OW
OH
OD
K.W.
K.W.
LBS
LBS
QD 524
16
18
25
12
11
20
11
11
20
54
75
56
13.5
10.0
110
2000
QD 814
19
15
25
15
9
20
14
8
20
57
72
57
14.0
10.0
125
2300
QD 824
19
21
25
15
15
20
14
14
20
57
84
57
17.0
12.0
150
2700
QD 836
19
21
37
15
15
32
14
14
32
57
84
69
22.5
17.5
200
3300
QD 236
25
21
37
21
15
32
20
14
32
63
84
73
27.0
21.0
300
3500
Dimensions are in inches. Weight is in pounds. 240 or 460 volts is normal. 208, 380 and 575 volts are optional. 3 phase is normal although single phase is available. Inside tempering chamber dimensions are also working dimensions for that chamber. Specifications are subject to change without notice.

OTHER SIMILAR FURNACES


PDF Brochures

Download PDF Brochure of the QD SERIES
(Large Dual Chamber Furnaces)

Download PDF Brochure of the QDH SERIES
(Large Dual Chamber Furnaces with high temperature tempering oven)

Download PDF Brochure of the QD29
(Our Smallest Dual Chamber Furnace)

Download PDF Brochure of the QDS SERIES
(Small Precision Dual Chamber Furnaces)

Download PDF Brochure of the QDG29
(2500 Deg F Hardening Chamber Dual Chamber Furnace)

Copyright © 2002, 2003 L&L Special Furnace Co., Inc.