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Old 1st October 2014, 11:58   #91
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Default Re: Sheet Metal Thickness - Does it matter?

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Originally Posted by saket77 View Post
If one is talking about Alto/ WagonR/ i10/Eon & the rest of the segment, there is no doubt that the structure will be unsafe too. However, I think that for the global offerings like the Swift/ City, the monocoque should be identical. Makes no financial sense to develop a different monocoque than an already researched one.
I did not mean that they would design a new monocoque, but would cut costs by using cheaper/weaker materials.
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Old 1st October 2014, 12:05   #92
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Default Re: Sheet Metal Thickness - Does it matter?

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Originally Posted by blacksport View Post
I did not mean that they would design a new monocoque, but would cut costs by using cheaper/weaker materials.
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Originally Posted by ajaypjayaraj View Post
It is a hybrid construction that manufacturers finally go for, to meet safety when it comes to structure. It is not purely monocoque. There are several add on safety members that contribute. So overall safety might not remain same if they make compromise in such areas. That is what I meant.
I think we have digressed quite from the topic at hand. At the absence of any test data exclusive to the very specific cars on Indian roads, it is difficult to prove anything conclusively.

But coming back to the topic, "Sheet metal thickness-Does it matter?", I would say no. I would believe, concurring with the NCAP researchers that for any car like Vento or a Fiesta or City, the rating would not change with change in sheet metal thickness. If the Fiesta has scored 5 stars with particular gauge of body panel sheets, I don't think it will score 4 or lesser with thinner body panels. The impact of body panels is minimal in crashes.
So, my final argument in the case is that with everything else remaining constant, sheet metal will not matter on the crash safety of a car.

Best Regards,
Saket
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Old 1st October 2014, 12:22   #93
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Default Re: Sheet Metal Thickness - Does it matter?

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Originally Posted by saket77 View Post
If one is talking about Alto/ WagonR/ i10/Eon & the rest of the segment, there is no doubt that the structure will be unsafe too. However, I think that for the global offerings like the Swift/ City, the monocoque should be identical. Makes no financial sense to develop a different monocoque than an already researched one.
Was just replying to that. That's where monocoque came into the picture in today's discussion.

Coming to the topic, it is very hard to separate sheet metal's contribution and other safety member's contribution towards overall safety of the car as the design is very complicated. And also, "thickness" is not the main thing here. Using light weight metals which are stronger might be less "thick" but same time more stronger right? So if one asks if "thickness" matters, I would be of the same opinion that it does not matter as long as the maker has taken care of the overall safety with such materials, design and construction.
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Old 1st October 2014, 12:46   #94
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Default Re: Sheet Metal Thickness - Does it matter?

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Originally Posted by atul.sxna View Post
A real-time crash involves a lot of factors that these tests do not take into account.

Scene 1:

..... Had it been your Jap or even our own Maruti, this post won't have made it to the forum.

I to-date thank God for saving my life and also for the fact that no one else was hurt due to that awe-full crash.

I swear by the strength of the sheet metal these Europeans use, I will buy a Ford / VW / Fiat with eyes closed any given day. I do not care that the upkeep of these vehicles might be more than those of Japs/Koreans but it is nothing compared to the safety they provide in a real time crash scenario.

DISCLAIMER : No alcohol was consumed at the time of crash. DO NOT DRINK AND DRINK is the mantra to live by.
Wow. The exact similar thing happened to my father in 2001. The only difference being, he was at 90-100 kmph with 4 people on board on a divided highway. Guess what. By the grace of God, all 4 people survived the crash with injuries only to my father. My father, since he had his hand on the window sill while the car somersaulted, his hand got bruised which required a plastic surgery. No other injury on any body part inside the cabin for all 4 members. The biggest surprise? The car involved was a humble 1997 Maruti 800. It was a total wreck and the garage quoted 80k for repairs (the monocoque remained intact even though there was extensive damage on the outside) for a vehicle with an IDV of just above a lakh. We repaired it just for the simple fact that it saved everyones life. It served us well till 2003 when we sold it.

Now you may generalize saying that Japs/especially Maruti is the epitome of cost cutting but for similar situations, the occupants walked out alive. Can I similarly generalize saying that Japs make safer cabins even with seemingly thinner sheet metal? I cannot and will not. Since accidents involve too many variables beyond the control of any manufacturer as you rightly said

Also a small request, can someone pls give me data supporting thinner sheet metal in the Asians, I do not want to judge it by the sound of doors closing. A 12 inch steel entrance door in my bank locker closes with a clunk because of poor dampening. I am sure no one can argue saying that Euros have thicker sheet metal that that door.
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Old 1st October 2014, 13:57   #95
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Default Re: Sheet Metal Thickness - Does it matter?

How about a plastic bodied german at 800 kg, against its bigger cousin acknowledged to be the pioneer in safety and comfort?

Going by the sheet thickness, and "popability", that smart should have fit in the owners pocket.



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Old 1st October 2014, 14:25   #96
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Default Re: Sheet Metal Thickness - Does it matter?

Quote:
Originally Posted by racer_ash View Post
A 12 inch steel entrance door in my bank locker closes with a clunk because of poor dampening. I am sure no one can argue saying that Euros have thicker sheet metal that that door.


Anyways what is meaning of sheet metal here? Are we talking about the outer skin of the car? The thin sheet which covers the whole car under it? If that is the thing in question here then I would say NO, that sheet metal doesn't matter at all.

What matters is the engineering involved in the structure design, the strength of the structural beams and other cross members, intelligent implantation of crumple zones. Apart from that, there is another thicker layer of metal sheet which definitely matters and that is usually covered behind door pads, dashboard etc.

The outer sheet metal will get damaged during impacts, thicker sheet may damage slightly lesser and thinner sheet may get damaged slightly worst. But the damage will be such that the cost of repairing will turn out almost equal.

I am rather in favor of eliminating usage of metal for outside skinning. Instead some other light weight material should be used for the outer covering of the car structure which can take few beatings without getting damaged during day to day usage and repairing costs can be brought down.

A slightest of kiss by other vehicles leaves significant scratch or dent on the metal panel which makes us feel sad. Then we want to get that scratch or dent fixed and cost comes in thousands. If some material like carbon fiber or something like that can be used then damage frequency will reduce significantly.

One example is Mahindra e2o.
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Old 1st October 2014, 15:03   #97
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Default Re: Sheet Metal Thickness - Does it matter?

Most of the "enthusiasts" would have gone thro' this article but neverthless....
Attached Thumbnails
Sheet Metal Thickness - Does it matter?-img_20141001_144812.jpg  

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Old 1st October 2014, 15:18   #98
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Default Re: Sheet Metal Thickness - Does it matter?

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Originally Posted by racer_ash View Post
Wow. The exact similar thing happened to my father in 2001. The only difference being, he was at 90-100 kmph with 4 people on board on a divided highway. Guess what. By the grace of God, all 4 people survived the crash with injuries only to my father. My father, since he had his hand on the window sill while the car somersaulted, his hand got bruised which required a plastic surgery. No other injury on any body part inside the cabin for all 4 members. The biggest surprise? The car involved was a humble 1997 Maruti 800. It was a total wreck and the garage quoted 80k for repairs (the monocoque remained intact even though there was extensive damage on the outside) for a vehicle with an IDV of just above a lakh. We repaired it just for the simple fact that it saved everyones life. It served us well till 2003 when we sold it.

Now you may generalize saying that Japs/especially Maruti is the epitome of cost cutting but for similar situations, the occupants walked out alive. Can I similarly generalize saying that Japs make safer cabins even with seemingly thinner sheet metal? I cannot and will not. Since accidents involve too many variables beyond the control of any manufacturer as you rightly said

Also a small request, can someone pls give me data supporting thinner sheet metal in the Asians, I do not want to judge it by the sound of doors closing. A 12 inch steel entrance door in my bank locker closes with a clunk because of poor dampening. I am sure no one can argue saying that Euros have thicker sheet metal that that door.
That's heartening to know dude, and good wishes to your family all round.

Like I said earlier, the general sense of security one (especially I) gets out of a thick body shell especially at high speeds cannot be achieved by its lightweight counterparts.

I guess, it's a good thing that this topic is being discussed with such varied and strong views and hopefully we as a community can bring about a change in the automobile industry.

NCAP tests though necessary are still at the end of the day conducted in a controlled environment.

Right now, we're debating on what we feel and not on data.
A lot of technical data with expert views is needed to arrive at a conclusive decision.

RANDOM THOUGHT: Can we ask the mods to build a general consensus on making the use of safety features standard for ALL cars sold in the Indian market. And then we utilize the strength of this forum to effect some changes in how the industry works.
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Old 1st October 2014, 15:24   #99
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Default Re: Sheet Metal Thickness - Does it matter?

For all those still in doubt, pls take a look at the PDF in the below link.

http://www.tatasteelautomotive.com/f...the_basics.pdf

I would ask you to directly jump to Pg 6 of the document and refer the diagram at the RHS.

The graph clearly points out to the members which are critical for passenger survival (RED) and which have good energy absorption (BLUE). As you all agree, efficient energy absorption by steel members is another vital factor in the survival of the occupants during a crash.

What we are fighting about are the parts shown in Green. Outer panels, which as per the article are there purely from aesthetics because these parts can be easily formed during a stamping process. In no way can these parts be expected to absorb the energies involved in a high speed crash. What we can clearly infer from the article is that thickness of sheet metal used for outer body panels (the ones that are visible to us) are never meant for crash resistance.

Also pls note, the Steels marked in RED have a Yield strength of more that 4 times the body panels. The article mentions 8Tonnes/sq.cm.
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Old 1st October 2014, 17:49   #100
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Default Re: Sheet Metal Thickness - Does it matter?

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Originally Posted by racer_ash View Post
The graph clearly points out to the members which are critical for passenger survival (RED) and which have good energy absorption (BLUE). As you all agree, efficient energy absorption by steel members is another vital factor in the survival of the occupants during a crash.

What we are fighting about are the parts shown in Green. Outer panels, which as per the article are there purely from aesthetics because these parts can be easily formed during a stamping process. In no way can these parts be expected to absorb the energies involved in a high speed crash. What we can clearly infer from the article is that thickness of sheet metal used for outer body panels (the ones that are visible to us) are never meant for crash resistance.

Also pls note, the Steels marked in RED have a Yield strength of more that 4 times the body panels. The article mentions 8Tonnes/sq.cm.
You're putting to dust all those arguments "developed" against low performance / efficiency etc that XYZ Manufacturer's cars saves lives (!!!) being safer cars for using thick sheet metal etc etc

On a more serious note, none of the manufacturers is saint. Neither European nor Asean manufacturers.

Do you think Europeans, when the sheet metal is thick in their cars, are doing it for Safety of it's customers? If they are so concerned about their customers' safety and put it on priority, then why not to give air bags as standard in the base models? How many are doing it? Heck, they even paddle the same European design LHD steering "as it is" in RHD cars in India to avoid minor changes required in redesign & development.

As for the ASEAN manufacturers, do they even give a thought that it gives a scary feeling driving many of those "light weight" cars at 140 kmph or above speeds on Indian highways?

Basically, this thread is all about the typical arguments used by two sections / groups on online forums against each other in such never-ending debates of not willing to accept weaknesses of their beloved car manufacturers

Last edited by TheIndian : 1st October 2014 at 17:52.
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Old 1st October 2014, 18:13   #101
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Default Re: Sheet Metal Thickness - Does it matter?

Quote:
Originally Posted by TheIndian View Post
Most of the "enthusiasts" would have gone thro' this article but neverthless....
Quote:
Originally Posted by racer_ash View Post
For all those still in doubt, pls take a look at the PDF in the below link.

http://www.tatasteelautomotive.com/f...the_basics.pdf

I would ask you to directly jump to Pg 6 of the document and refer the diagram at the RHS.

The graph clearly points out to the members which are critical for passenger survival (RED) and which have good energy absorption (BLUE). As you all agree, efficient energy absorption by steel members is another vital factor in the survival of the occupants during a crash.

What we are fighting about are the parts shown in Green. Outer panels, which as per the article are there purely from aesthetics because these parts can be easily formed during a stamping process. In no way can these parts be expected to absorb the energies involved in a high speed crash. What we can clearly infer from the article is that thickness of sheet metal used for outer body panels (the ones that are visible to us) are never meant for crash resistance.

Also pls note, the Steels marked in RED have a Yield strength of more that 4 times the body panels. The article mentions 8Tonnes/sq.cm.
Thank you you the information. However, this will get buried in the pages and people will continue to fight on Europeans and Asian manufacturers without going through the entire discussion. There shall either be way to put up all the important information, like these, on top of each page or the discussion should happen strictly on technical basis/data rather on how one 'feel'.

I wish we have the crash test data of all cars on sale in India to be able to decide on the future car. As of now, one can not buy a car based on the findings of this thread.

Last edited by sourabhzen : 1st October 2014 at 18:15.
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Old 1st October 2014, 18:46   #102
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Default Re: Sheet Metal Thickness - Does it matter?



An interesting video on this topic.
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Old 2nd October 2014, 16:21   #103
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Default Re: Sheet Metal Thickness - Does it matter?

While discussing sheet metal should we also be worried about corrosion?

I have a WagonR which had rust issues, I had posted on another thread, It had rusted and corroded on the dashboard area. (I know we are discussing the likes of Swift/City/ Punto etc.).

The garage guy told me that Marutis in Mumbai had a history with rust and that the panels used are very thin.

Now will corrosion be a factor in safety if, let's say, the accident happens after 4 years of ownership.

This has lead me to avoid Marutis from my future purchases, unless a review boasts about build quality.

PS: I stay in Mumbai and know that corrosion will be a factor in coastal areas areas only.
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Old 2nd October 2014, 17:52   #104
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Originally Posted by Slick View Post
While discussing sheet metal should we also be worried about corrosion?

I have a WagonR which had rust issues, I had posted on another thread, It had rusted and corroded on the dashboard area. (I know we are discussing the likes of Swift/City/ Punto etc.).

The garage guy told me that Marutis in Mumbai had a history with rust and that the panels used are very thin.

Now will corrosion be a factor in safety if, let's say, the accident happens after 4 years of ownership.

This has lead me to avoid Marutis from my future purchases, unless a review boasts about build quality.

PS: I stay in Mumbai and know that corrosion will be a factor in coastal areas areas only.

Yes, corrosion is a factor relating to safety. And no, corrosion is not limited to coastal areas only. Its just much worse in coastal areas. My wife grew up in Barbados, a tiny island in the West Indies, completely surrounded by sea and oceans. You wont believe what that does to not only cars, but everything, including houses.

In most western countries there a yearly test inspection done on your car. Mainly to do about safety and emissions. In the UK known as MOT, in the Netherlands APK etc. Usually starts after your car is a few years old and then continuous for every year. In some countries classic cars are exempt or require fewer test, such as every other year.

Back to corrosion and safety. During these inspection they will look for corrosion in critical areas. So some rust, even badly rusted through say body panel, a door or a boot is no problem. But rust / corrosion on structural parts of your car will affect its strength and thus its safety. Too much in the wrong place and your car wont pass its MOT.

So, yes corrosion is something you need to weary of, especially on those parts of the cars that are part of its structural integrity and thus safety.

Jeroen
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Old 2nd October 2014, 20:20   #105
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Default Re: Sheet Metal Thickness - Does it matter?

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Originally Posted by D4D View Post
  • Ultimately it's the underlying frame and it's design that's crucial
  • Sheet metal is like your skin over your skeleton It is meant to take light impact
  • NCAP tests will determine the effectiveness of the crumple zones in your car. At crash speeds, the extra 0.5~1 mm in the sheet metal is not going to much of a difference
  • ......
  • European priorities are different compared to Japanese priorities. Europeans have a great attention to detail to each and every aspect of a car. The cars are meant to be premium
  • Japanese look to squeeze the maximum out of the last drop of fuel and use as much less power as possible. The are efficiency conscious, so they will compromise on sheet metal. It shouldn't matter that much

Quote:
Originally Posted by diffsoft View Post
From reading the opening thread and subsequent posts, it appears the crux of the arguments is that if Japanese / Korean cars can produce the same NCAP ratings as their European counterpart, then why do European cars make a big deal of the European's sheet metal thickness?

However this presumes that sheet metal thickness is solely for the purpose of safety.

But that presumption is incorrect. Sheet metal thickness provides for greater rigidity and body durability. That (along with laser seam welding for the top) provides for keeping the car shell in the same shape for a longer time to come. I have seen the older Honda Citys outer body flexed at various places with age. Our family's 21 month Ertiga suffers from many minor scars showing its age even though nothing of significance has hit the car's sheet metal yet; a minor nudge from a two-wheeler and the wrinkle shows.

......

To conclude sheet metal may or may not be a big deal for NCAP safety but it helps to keep the car the same from outside for a longer time.

Cheers,
+1 to the above comments.

Quote:
Originally Posted by nakul0888 View Post

Besides that has got nothing to do with sheet metal thickness, isn't it?

.....
Quote:
Originally Posted by saket77 View Post
Dear Crazy Driver,

Totally understand the concept of modifiers in the test. Of course, I never meant that the car was modified in some way to pass the test. Apologies if I sounded so, inadvertently.
Also, the thread was not about the Vento Vs. City. It was about Thinner vs. Thicker skin. I just wanted to convey that external body panels do not play any significant role in the car's performance in the crash. Also, another food for thought from the data which I gave in my comparison report of Vento & City should make us think if we are indeed buying the same Vento here as in other countries. Indeed, it is not the same City we buy here, but again, not the same Vento too. And that was an eye opener for me, if not for someone else.

If the thread title is the only thing to summarize, then forgetting the ventos & the citys and the fiestas, all I can say that everything else remaining the same, the thinner or thicker sheet panels DO NOT MATTER for crash safety. I have already quoted my source which is the NCAP itself. Quoting it again to finish my argument:


(Source: Australian NCAP; http://www.ancap.com.au/faqs)

Thanks,
Saket
Nakul0888's topic has taken a slight different route as I could make out. I understand that he took VW and Honda as examples for his discussion around thinner and thicker sheets (Saket77 summed it up pretty well as well).

Do I feel safe holding the wheels of a VW/Fiat as against the Asian rivals?
Answer: Yes, I do feel the sturdiness in their machines, and it gives me some amount of confidence.

Does that mean VW/Fiat is more safe?
Anwer: I do not think so!

Many have already stated their opinion on the sheet metal thickness, monocoque, crumble zones, etc. which is dead right.

And I feel it is worthless to keep continuing American Vs European Vs Asian debate in this thread. It does not make any sense (at least to me). It's a typical case of "Analysis Paralysis". Period! Now again, do not read too much between the lines, and misunderstand me. Numbers do matter, its just that the permutations & combinations on them could lead us astray.

I am glad that Nakul brought this topic. Thank you.
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