close loop after each term

page-lathes.php

<?php
/**
 * Theme: Flat Bootstrap
 * 
* Template Name: ACF Lathes
 *
 * This is the most generic template file in a WordPress theme
 * and one of the two required files for a theme (the other being style.css).
 * It is used to display a page when nothing more specific matches a query.
 * E.g., it puts together the home page when no home.php file exists.
 * Learn more: http://codex.wordpress.org/Template_Hierarchy
 *
 * @package flat-bootstrap
 */

get_header(); ?>

<?php get_template_part( 'content', 'header' ); ?>
<div class="container">
<div id="main-grid" class="row">

	<section id="primary" class="content-area col-md-8">
		<main id="main" class="site-main" role="main">
<?php 
wp_reset_postdata();
$term_id = 20;
$tax_name = 'category';
$termchildren = get_term_children( $term_id, $tax_name );

$i=1;
foreach ( $termchildren as $child ) {
echo '<div class="'. $i . '-term">';
	$child_term = get_term_by( 'id', $child, $tax_name );

 $args = array(
	'post_type' => 'inventory',
	'tax_query' => array(
		array(
			'taxonomy' => 'category',
			'field'    => 'slug',
			'terms'    => $child_term->slug,
		),
	),
);

$query = new WP_Query( $args );
?><div class="<?php echo $i; ?>-post">
<?php // output the term name in a heading tag                
    echo'<h2 style="background:#94A6C6;padding:5px 0 5px 20px;font-weight:bold;">' . $child_term->name . '</h2>';
     
        // Start the Loop
        while ( $query->have_posts() ) : $query->the_post(); ?>
 
        <div class="<?php echo $child_term->name; ?>-listing" id="post-<?php the_ID(); ?>">
				<div class="post-thumb" style="width:27%;float:left;">
					<a href="<?php the_permalink(); ?>"><?php 
						if ( has_post_thumbnail() ) { // check if the post has a Post Thumbnail assigned to it.
							the_post_thumbnail('inventory-size');
						}  ?>
					</a>
				</div>
				<div class="post-content">
					<a href="<?php the_permalink(); ?>">
						<h4><?php the_field('name') ?></h4>
					</a>
				</div>
         </div>

        <?php 

		endwhile;
	echo '</div>'; $i++;
    // use reset postdata to restore orginal query
    wp_reset_postdata();
} 
?>
		</main><!-- #main -->
	</section><!-- #primary -->

	<?php get_sidebar(); ?>

</div><!-- .row -->
</div><!-- .container -->

<?php get_footer(); ?>