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8 comments
Commentator

Join Date: Dec 2007
Posts: 75

Gearbox Replacement

02/21/2008 11:06 AM

I am currently assembling a new 45mm extruder 28:1 for LLDPE & LDPE profile extrusion. I just oredered a set of screw and barrel. My first option is to couple it to a gearbox 30:1 (for speed reduction) w/ V.F.C.. Unfortunately, gearbox prices here in P.I. has become prohibitive. A surplus japan used gearbox costs UD$1,500.00 with no idea as to it's running condition (as is, where is). A brand new Taiwan made gearbox costs US$3,000.00. I am comtemplating on using the following alternatives:

1. Use a DC motor.

2. Use a servo motor.

3.Use a surplus military Reo 6x6 tranny.

Given:

1. My old 45mm extruder runs on a 5hp motor.

2. Production is 24hrs, 7 days a week.

Worries:

1. Some say that the 60rpm i need for DC or servo motor would produce a very low torque.

2. The surplus military tranny might not hold up to my 24 hour operation.

I need your inputs as to which is a better solution or probably you could give me other/new options & insights besides what i have stated.

Thanks in advance.

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Pathfinder Tags: Extrusion gear gearbox plastic profile reducer speed
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Guru
Engineering Fields - Systems Engineering - New Member Hobbies - Model Rocketry - New Member

Join Date: Dec 2006
Location: Long.92E,Lat.26N
Posts: 1295
Good Answers: 13
#1

Re: Gearbox Replacement

02/22/2008 12:15 AM

<

<1. My old 45mm extruder runs on a 5hp motor.

2. Production is 24hrs, 7 days a week.

Worries:

1. Some say that the 60rpm i need for DC or servo motor would produce a very low torque.

2. The surplus military tranny might not hold up to my 24 hour operation.

I need your inputs as to which is a better solution or probably you could give me other/new options & insights besides what i have stated>

45 mm Extruder commercially today will be supplied with a 20KW Cont.Rated drive! But probably yours worked with LLdpe /HDPE. So 5HP is what we will talk about:

DC Motor - low Torque?--On the contrary- you can control Armature and Field to get many Torques and many speeds

surplus military tranny might not hold up to my 24 hour :

MIL =Overrated/RuggEdized -- isn't that the rule? Should work!

If you want a factory- fresh 5 HP 415V 3ph 50Hz Cont Duty coaxial shaft Panetary Gearmotor from India -- I can ask a producer to quote direct to you. What max RPM(if fed 50/60Hz). You will use VFD?

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Commentator

Join Date: Dec 2007
Posts: 75
#2
In reply to #1

Re: Gearbox Replacement

02/22/2008 6:29 AM

45 mm Extruder commercially today will be supplied with a 20KW Cont.Rated drive!

- do you mean a 20kw induction motor?

So 5HP is what we will talk about:

- i am open to suggestions especially if you feel that a 5hp motor is too weak. The only reason i started with a 5hp motor because electricity cost here in P.I. is expensive. I'm not sure if the gains from production i would be getting from a bigger motor would still fit my cost.

DC Motor - low Torque?--On the contrary- you can control Armature and Field to get many Torques and many speeds

- So this is an option. Can i couple it directly behind the screw to avoid speed reducers? If yes, what motor rating for a DC motor can you suggest?

MIL =Overrated/RuggEdized -- isn't that the rule? Should work!

- i guess so. Thanks.

If you want a factory- fresh 5 HP 415V 3ph 50Hz Cont Duty coaxial shaft Panetary Gearmotor from India -- I can ask a producer to quote direct to you.

- Sure! Honestly, i'm not an engineer. I based my designs and specs on actual experience. I hope you don't mind. We have an input of 220vac, 3 phase, 60 cycle electricity.

What max RPM(if fed 50/60Hz).

- 50-80 RPM @ 60hz.

You will use VFD?

- Yes. I always use V.F.D. controller for all my extruder and conveyor induction motors.

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Guru
Engineering Fields - Systems Engineering - New Member Hobbies - Model Rocketry - New Member

Join Date: Dec 2006
Location: Long.92E,Lat.26N
Posts: 1295
Good Answers: 13
#4
In reply to #2

Re: Gearbox Replacement

02/22/2008 8:59 PM

Please look at this:

Arburg 305-210-700

Sarac Code 5049

70 Ton Clamp OpeningStroke 250 Screw35mm,

120gm /shot

11 KW motor

8,5 KW heaters

Arburg 270-90-500

Sarac Code 5096

50 Ton Clamp, Opening Stroke 325 Screw 35mm, 121gm /shot 15 KW motor

9.6 KW heaters

Demag D 85

Sarac Code 5198

85 TonClamp,

Opening Stroke 350

Screw 38 mm,

145gm /shot

22 KW motor

10.8 KW heaters

SUMO Smart-(2004) Windsor 75T Clamp

Opening Stroke 300

Screw 36 mm,

136 gm/shot

15 KW motor

5.7 KW heaters

If you say you did OK witha5HP DRIVE--fine- you can have it.

If you invested already in VFD, and you have 220V 3Φ 60HZ-you won't get motors to that spec in India. Better US used motor say 10HP3500rpm(small frame size-check if you have roomto mount. Now all you need is the small efficient Planetary Gear reducer to bring speed down from 3500 to say70. That is possible to get flown in from India -- if you cannot get one locally.

Cost of transportation will be around $500?

If now you can give the Injector Screw intake spline/keyway detail and motor Shaft output detail and the heihgt of Gearbox frombase to centreline-- somebody can sell you the gear Reducer.

Please send all these + your E-mailID+Address.

Thanks

MM

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Commentator

Join Date: Dec 2007
Posts: 75
#6
In reply to #4

Re: Gearbox Replacement

02/25/2008 6:43 AM

Mukulmahant;

The specs are for injection moulding. mine is extrusion. But i still get your picture. thanks. I'll try to research more on planetary gears. Do you have a link explaning planetay gears? We might have planetary gears here in P.I. Are car differentials made of planetary gears?

Thanks.

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Commentator

Join Date: Sep 2007
Location: Brampton, ON, Canada
Posts: 88
Good Answers: 2
#3

Re: Gearbox Replacement

02/22/2008 8:59 AM

Hi,

The prices you have quoted for gearboxes are very reasonable. Extruders are very hard on gearboxes and 24/7 again puts quite a strain on the box. A good gearbox on a well maintained extruder should last you 20 years. This is not a component you should try to save money on!

The DC motor or servo will draw too many Amps to run at 60 rpm on an extruder. Your electricity costs will pay for the gearbox in about one week!

There is an italian extruder supplier Machhi, who has worked with Seimens to develop a low rpm motor to run an extruder without the use of a gearbox. However the cost is again much more than what the gearbox will cost.

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Anonymous Poster
#5
In reply to #3

Re: Gearbox Replacement

02/23/2008 12:56 PM

I know nothing of what you are talking about but these people might have a solution. Motor and Gear Engineering, Inc (770) 454-9001. They might have a rebuild that would save money. motorgearengineer.com is website.

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Anonymous Poster
#7

Re: Gearbox Replacement

02/25/2008 1:40 PM

A gearbox will work much better than the VFD for an Extrusion operation.

The VFD will tend to not deliver enough torque at the rated speed,

If you can't afford the new gearbox getout of the business.

We have a saying:

Used Equipment only costs a little bit more than New Equipment

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Commentator

Join Date: Dec 2007
Posts: 75
#8
In reply to #7

Re: Gearbox Replacement

02/26/2008 2:33 AM

to guest:

Hi. A formal introduction as to who you are might be appropriate rather than talking to a "guest". Try registering or logging in and you'll learn more.

A gearbox will work much better than the VFD for an Extrusion operation.

- I think it's the other way around. A VFD will work better with a gearbox.

The VFD will tend to not deliver enough torque at the rated speed,

- Yes.

If you can't afford the new gearbox getout of the business.

- Personally, besides being RUDE, you are definitely OUT-OF-THE-TOPIC. I am merely exploring the possibilities and options re my project. I think this is the purpose of this forum. To ask and share some ideas be it old, cheap, innovative and the like. And if you would be brave enough to answer all inquiries like the way you reply, then i think you DO NOT BELONG to this forum at all.

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